These data are made available to the scientific community and public with the understanding that authors of publications and presentations will contact the PI to obtain up-to-date information on the latest version of the data during the early stages of their analysis. Manuscripts that employ these data should be reviewed by the PI before submission to ensure the quality and limitations of the data are represented. Data Disclaimer: Data has undergone extensive quality checks and is available from NOAA-GMD and WDCGG. However, there still exists the potential for these data to be modified at the discretion of NOAA/ESRL Global Monitoring Division. If you have questions regarding the data in this file, please contact: Audra McClure-Begley: Audra.mcclure@noaa.gov (303-497-6823) Please use the following citation for data use: McClure-Begley, A., Petropavlovskikh, I., Oltmans, S., (2014) NOAA Global Monitoring Surface Ozone Network. Station name, Time start-Time end. National Oceanic and Atmospheric Administration, Earth Systems Research Laboratory Global Monitoring Division. Boulder, CO. DATE ACCESSED http://dx.doi.org/10.7289/V57P8WBF STN YEAR MON DAY HR O3(PPB) SUM 2013 09 01 00 34.93 SUM 2013 09 01 01 35.05 SUM 2013 09 01 02 35.03 SUM 2013 09 01 03 34.91 SUM 2013 09 01 04 34.92 SUM 2013 09 01 05 35.06 SUM 2013 09 01 06 34.93 SUM 2013 09 01 07 34.59 SUM 2013 09 01 08 34.52 SUM 2013 09 01 09 34.67 SUM 2013 09 01 10 34.87 SUM 2013 09 01 11 34.48 SUM 2013 09 01 12 34.31 SUM 2013 09 01 13 34.43 SUM 2013 09 01 14 34.46 SUM 2013 09 01 15 34.20 SUM 2013 09 01 16 34.14 SUM 2013 09 01 17 34.15 SUM 2013 09 01 18 34.28 SUM 2013 09 01 19 34.40 SUM 2013 09 01 20 34.38 SUM 2013 09 01 21 34.23 SUM 2013 09 01 22 34.62 SUM 2013 09 01 23 39.71 SUM 2013 09 02 00 41.46 SUM 2013 09 02 01 41.31 SUM 2013 09 02 02 41.84 SUM 2013 09 02 03 41.47 SUM 2013 09 02 04 40.87 SUM 2013 09 02 05 40.63 SUM 2013 09 02 06 40.92 SUM 2013 09 02 07 41.42 SUM 2013 09 02 08 40.73 SUM 2013 09 02 09 39.84 SUM 2013 09 02 10 39.82 SUM 2013 09 02 13 39.25 SUM 2013 09 02 14 39.18 SUM 2013 09 02 15 39.02 SUM 2013 09 02 16 38.81 SUM 2013 09 02 17 38.31 SUM 2013 09 02 18 38.21 SUM 2013 09 02 19 38.59 SUM 2013 09 02 20 37.97 SUM 2013 09 02 21 37.64 SUM 2013 09 02 22 40.19 SUM 2013 09 02 23 40.00 SUM 2013 09 03 00 37.74 SUM 2013 09 03 01 38.18 SUM 2013 09 03 02 38.39 SUM 2013 09 03 03 39.06 SUM 2013 09 03 04 40.07 SUM 2013 09 03 05 39.92 SUM 2013 09 03 06 39.92 SUM 2013 09 03 07 39.90 SUM 2013 09 03 08 39.35 SUM 2013 09 03 09 39.53 SUM 2013 09 03 10 39.85 SUM 2013 09 03 11 39.33 SUM 2013 09 03 12 38.33 SUM 2013 09 03 13 38.40 SUM 2013 09 03 14 38.75 SUM 2013 09 03 15 39.91 SUM 2013 09 03 16 39.15 SUM 2013 09 03 17 39.21 SUM 2013 09 03 18 38.98 SUM 2013 09 03 19 38.75 SUM 2013 09 03 20 39.31 SUM 2013 09 03 21 39.57 SUM 2013 09 03 22 39.18 SUM 2013 09 03 23 38.90 SUM 2013 09 04 00 38.76 SUM 2013 09 04 01 38.94 SUM 2013 09 04 02 38.91 SUM 2013 09 04 03 39.14 SUM 2013 09 04 04 38.88 SUM 2013 09 04 05 39.49 SUM 2013 09 04 06 40.47 SUM 2013 09 04 07 40.94 SUM 2013 09 04 08 41.16 SUM 2013 09 04 09 42.57 SUM 2013 09 04 10 43.88 SUM 2013 09 04 11 43.46 SUM 2013 09 04 12 43.69 SUM 2013 09 04 13 43.71 SUM 2013 09 04 14 43.30 SUM 2013 09 04 15 43.51 SUM 2013 09 04 16 43.71 SUM 2013 09 04 17 43.23 SUM 2013 09 04 18 43.01 SUM 2013 09 04 19 43.10 SUM 2013 09 04 20 42.76 SUM 2013 09 04 21 41.77 SUM 2013 09 04 22 40.87 SUM 2013 09 04 23 41.47 SUM 2013 09 05 00 42.28 SUM 2013 09 05 01 42.87 SUM 2013 09 05 02 44.08 SUM 2013 09 05 03 44.63 SUM 2013 09 05 04 44.36 SUM 2013 09 05 05 43.50 SUM 2013 09 05 06 44.08 SUM 2013 09 05 07 44.41 SUM 2013 09 05 08 45.00 SUM 2013 09 05 09 44.70 SUM 2013 09 05 10 44.32 SUM 2013 09 05 11 44.14 SUM 2013 09 05 12 43.00 SUM 2013 09 05 13 42.56 SUM 2013 09 05 14 41.27 SUM 2013 09 05 15 42.21 SUM 2013 09 05 16 41.70 SUM 2013 09 05 17 40.70 SUM 2013 09 05 18 40.74 SUM 2013 09 05 19 41.15 SUM 2013 09 05 20 41.60 SUM 2013 09 05 21 42.79 SUM 2013 09 05 22 43.72 SUM 2013 09 05 23 43.95 SUM 2013 09 06 00 43.88 SUM 2013 09 06 01 44.10 SUM 2013 09 06 02 44.00 SUM 2013 09 06 03 43.36 SUM 2013 09 06 04 43.13 SUM 2013 09 06 05 42.73 SUM 2013 09 06 06 43.97 SUM 2013 09 06 07 43.17 SUM 2013 09 06 08 42.95 SUM 2013 09 06 09 43.71 SUM 2013 09 06 10 43.96 SUM 2013 09 06 11 41.98 SUM 2013 09 06 12 42.96 SUM 2013 09 06 13 42.64 SUM 2013 09 06 14 42.14 SUM 2013 09 06 15 42.99 SUM 2013 09 06 16 43.75 SUM 2013 09 06 17 43.13 SUM 2013 09 06 18 42.36 SUM 2013 09 06 19 42.15 SUM 2013 09 06 20 43.11 SUM 2013 09 06 21 47.44 SUM 2013 09 06 22 50.75 SUM 2013 09 06 23 48.99 SUM 2013 09 07 00 48.85 SUM 2013 09 07 01 51.10 SUM 2013 09 07 02 47.54 SUM 2013 09 07 03 45.64 SUM 2013 09 07 04 46.60 SUM 2013 09 07 05 46.02 SUM 2013 09 07 06 44.07 SUM 2013 09 07 07 43.41 SUM 2013 09 07 08 43.84 SUM 2013 09 07 09 42.56 SUM 2013 09 07 10 42.12 SUM 2013 09 07 11 44.92 SUM 2013 09 07 12 45.61 SUM 2013 09 07 13 44.77 SUM 2013 09 07 14 42.67 SUM 2013 09 07 15 41.51 SUM 2013 09 07 16 40.95 SUM 2013 09 07 17 40.81 SUM 2013 09 07 18 39.92 SUM 2013 09 07 19 40.15 SUM 2013 09 07 20 39.56 SUM 2013 09 07 21 36.66 SUM 2013 09 07 22 35.59 SUM 2013 09 07 23 35.51 SUM 2013 09 08 00 35.43 SUM 2013 09 08 01 34.71 SUM 2013 09 08 02 34.43 SUM 2013 09 08 03 33.62 SUM 2013 09 08 04 33.78 SUM 2013 09 08 05 33.55 SUM 2013 09 08 06 32.64 SUM 2013 09 08 07 32.38 SUM 2013 09 08 08 32.17 SUM 2013 09 08 09 31.91 SUM 2013 09 08 10 31.37 SUM 2013 09 08 11 31.06 SUM 2013 09 08 12 31.11 SUM 2013 09 08 13 31.70 SUM 2013 09 08 14 31.79 SUM 2013 09 08 15 31.60 SUM 2013 09 08 16 32.41 SUM 2013 09 08 17 33.24 SUM 2013 09 08 18 33.83 SUM 2013 09 08 19 34.74 SUM 2013 09 08 20 35.69 SUM 2013 09 08 21 37.85 SUM 2013 09 08 22 40.80 SUM 2013 09 08 23 42.23 SUM 2013 09 09 00 42.95 SUM 2013 09 09 01 40.42 SUM 2013 09 09 02 38.30 SUM 2013 09 09 03 36.90 SUM 2013 09 09 04 35.18 SUM 2013 09 09 05 33.55 SUM 2013 09 09 06 35.10 SUM 2013 09 09 07 36.49 SUM 2013 09 09 08 37.56 SUM 2013 09 09 09 38.07 SUM 2013 09 09 10 40.22 SUM 2013 09 09 13 44.35 SUM 2013 09 15 02 36.88 SUM 2013 09 15 03 37.89 SUM 2013 09 15 04 37.19 SUM 2013 09 15 05 38.20 SUM 2013 09 15 06 37.86 SUM 2013 09 15 07 38.18 SUM 2013 09 15 08 37.92 SUM 2013 09 15 09 37.64 SUM 2013 09 15 10 37.61 SUM 2013 09 15 11 37.61 SUM 2013 09 15 12 37.56 SUM 2013 09 15 13 37.53 SUM 2013 09 15 14 37.43 SUM 2013 09 15 15 37.78 SUM 2013 09 15 16 38.12 SUM 2013 09 15 17 38.10 SUM 2013 09 15 18 38.08 SUM 2013 09 15 19 38.00 SUM 2013 09 15 20 36.80 SUM 2013 09 15 21 35.81 SUM 2013 09 15 22 37.30 SUM 2013 09 15 23 37.79 SUM 2013 09 16 00 37.43 SUM 2013 09 16 01 37.26 SUM 2013 09 16 02 37.96 SUM 2013 09 16 03 39.65 SUM 2013 09 16 04 39.25 SUM 2013 09 16 05 39.31 SUM 2013 09 16 06 38.84 SUM 2013 09 16 07 38.95 SUM 2013 09 16 08 37.65 SUM 2013 09 16 09 37.63 SUM 2013 09 16 10 37.21 SUM 2013 09 16 13 36.03 SUM 2013 09 16 14 36.33 SUM 2013 09 16 15 36.41 SUM 2013 09 16 16 36.37 SUM 2013 09 16 17 36.44 SUM 2013 09 16 18 36.60 SUM 2013 09 16 19 36.70 SUM 2013 09 16 20 36.91 SUM 2013 09 16 21 37.12 SUM 2013 09 16 22 37.37 SUM 2013 09 16 23 37.92 SUM 2013 09 17 00 38.07 SUM 2013 09 17 01 38.15 SUM 2013 09 17 02 38.06 SUM 2013 09 17 03 38.37 SUM 2013 09 17 04 38.36 SUM 2013 09 17 05 38.52 SUM 2013 09 17 06 38.45 SUM 2013 09 17 07 38.40 SUM 2013 09 17 08 38.33 SUM 2013 09 17 09 38.07 SUM 2013 09 17 10 37.78 SUM 2013 09 17 11 37.56 SUM 2013 09 17 12 37.85 SUM 2013 09 17 13 37.67 SUM 2013 09 17 14 37.57 SUM 2013 09 17 15 37.10 SUM 2013 09 17 16 36.96 SUM 2013 09 17 17 36.37 SUM 2013 09 17 18 36.90 SUM 2013 09 17 19 38.44 SUM 2013 09 17 20 38.59 SUM 2013 09 17 21 38.87 SUM 2013 09 17 22 38.52 SUM 2013 09 17 23 38.24 SUM 2013 09 18 00 38.06 SUM 2013 09 18 01 38.44 SUM 2013 09 18 02 39.01 SUM 2013 09 18 03 39.83 SUM 2013 09 18 04 42.41 SUM 2013 09 18 05 44.84 SUM 2013 09 18 06 44.77 SUM 2013 09 18 07 44.63 SUM 2013 09 18 08 44.04 SUM 2013 09 18 09 43.73 SUM 2013 09 18 10 43.71 SUM 2013 09 18 11 44.02 SUM 2013 09 18 12 44.36 SUM 2013 09 18 13 44.58 SUM 2013 09 18 14 44.58 SUM 2013 09 18 15 43.43 SUM 2013 09 18 16 43.26 SUM 2013 09 18 17 43.04 SUM 2013 09 18 18 42.66 SUM 2013 09 18 19 42.22 SUM 2013 09 18 20 41.63 SUM 2013 09 18 21 41.21 SUM 2013 09 18 22 41.15 SUM 2013 09 18 23 41.23 SUM 2013 09 19 00 41.29 SUM 2013 09 19 01 41.29 SUM 2013 09 19 02 41.18 SUM 2013 09 19 03 41.21 SUM 2013 09 19 04 41.12 SUM 2013 09 19 05 42.17 SUM 2013 09 19 06 44.21 SUM 2013 09 19 07 45.74 SUM 2013 09 19 08 46.75 SUM 2013 09 19 09 46.77 SUM 2013 09 19 10 46.44 SUM 2013 09 19 11 47.65 SUM 2013 09 19 12 49.40 SUM 2013 09 19 13 49.49 SUM 2013 09 19 14 49.24 SUM 2013 09 19 15 49.01 SUM 2013 09 19 16 48.79 SUM 2013 09 19 17 48.05 SUM 2013 09 19 18 47.39 SUM 2013 09 19 19 46.54 SUM 2013 09 19 20 45.09 SUM 2013 09 19 21 45.09 SUM 2013 09 19 22 45.47 SUM 2013 09 19 23 44.73 SUM 2013 09 20 00 44.66 SUM 2013 09 20 01 44.49 SUM 2013 09 20 02 44.06 SUM 2013 09 20 03 43.79 SUM 2013 09 20 04 43.62 SUM 2013 09 20 05 42.56 SUM 2013 09 20 06 41.89 SUM 2013 09 20 07 41.69 SUM 2013 09 20 08 41.42 SUM 2013 09 20 09 42.92 SUM 2013 09 20 10 42.51 SUM 2013 09 20 11 42.74 SUM 2013 09 20 12 43.03 SUM 2013 09 20 13 43.69 SUM 2013 09 20 14 43.80 SUM 2013 09 20 15 43.87 SUM 2013 09 20 16 43.99 SUM 2013 09 20 17 44.26 SUM 2013 09 20 18 44.31 SUM 2013 09 20 19 44.45 SUM 2013 09 20 20 44.44 SUM 2013 09 20 21 44.15 SUM 2013 09 20 22 44.24 SUM 2013 09 20 23 44.20 SUM 2013 09 21 00 44.23 SUM 2013 09 21 01 44.22 SUM 2013 09 21 02 44.18 SUM 2013 09 21 03 44.19 SUM 2013 09 21 04 44.11 SUM 2013 09 21 05 44.20 SUM 2013 09 21 06 43.81 SUM 2013 09 21 07 44.11 SUM 2013 09 21 08 44.60 SUM 2013 09 21 09 44.79 SUM 2013 09 21 10 44.72 SUM 2013 09 21 11 44.52 SUM 2013 09 21 12 44.67 SUM 2013 09 21 13 44.68 SUM 2013 09 21 14 44.63 SUM 2013 09 21 15 44.68 SUM 2013 09 21 16 44.58 SUM 2013 09 21 17 44.64 SUM 2013 09 21 18 44.50 SUM 2013 09 21 19 43.80 SUM 2013 09 21 20 42.11 SUM 2013 09 21 21 42.13 SUM 2013 09 21 22 41.26 SUM 2013 09 21 23 39.33 SUM 2013 09 22 00 38.76 SUM 2013 09 22 01 38.88 SUM 2013 09 22 02 40.68 SUM 2013 09 22 03 41.52 SUM 2013 09 22 04 41.86 SUM 2013 09 22 05 43.06 SUM 2013 09 22 06 43.10 SUM 2013 09 22 07 40.65 SUM 2013 09 22 08 38.89 SUM 2013 09 22 09 39.49 SUM 2013 09 22 10 43.06 SUM 2013 09 22 11 43.79 SUM 2013 09 22 12 40.94 SUM 2013 09 22 13 39.33 SUM 2013 09 22 14 38.89 SUM 2013 09 22 15 39.41 SUM 2013 09 22 16 39.64 SUM 2013 09 22 17 40.36 SUM 2013 09 22 18 40.96 SUM 2013 09 22 19 41.49 SUM 2013 09 22 20 42.04 SUM 2013 09 22 21 42.75 SUM 2013 09 22 22 42.85 SUM 2013 09 22 23 42.73 SUM 2013 09 23 00 42.29 SUM 2013 09 23 01 41.85 SUM 2013 09 23 02 41.75 SUM 2013 09 23 03 41.88 SUM 2013 09 23 04 42.43 SUM 2013 09 23 05 43.25 SUM 2013 09 23 06 43.40 SUM 2013 09 23 07 43.24 SUM 2013 09 23 08 42.77 SUM 2013 09 23 09 42.40 SUM 2013 09 23 12 41.63 SUM 2013 09 23 13 41.68 SUM 2013 09 23 14 41.83 SUM 2013 09 23 15 41.88 SUM 2013 09 23 16 42.03 SUM 2013 09 23 17 42.45 SUM 2013 09 23 18 42.70 SUM 2013 09 23 19 43.03 SUM 2013 09 23 20 42.73 SUM 2013 09 23 21 42.45 SUM 2013 09 23 22 41.41 SUM 2013 09 23 23 41.18 SUM 2013 09 24 00 41.86 SUM 2013 09 24 01 42.79 SUM 2013 09 24 02 43.69 SUM 2013 09 24 03 44.34 SUM 2013 09 24 04 43.52 SUM 2013 09 24 05 42.29 SUM 2013 09 24 06 41.62 SUM 2013 09 24 07 42.29 SUM 2013 09 24 08 42.68 SUM 2013 09 24 09 42.07 SUM 2013 09 24 10 41.19 SUM 2013 09 24 11 40.61 SUM 2013 09 24 12 40.17 SUM 2013 09 24 13 40.30 SUM 2013 09 24 14 40.57 SUM 2013 09 24 15 40.58 SUM 2013 09 24 16 40.52 SUM 2013 09 24 17 40.49 SUM 2013 09 24 18 40.52 SUM 2013 09 24 19 40.61 SUM 2013 09 24 20 40.62 SUM 2013 09 24 21 40.61 SUM 2013 09 24 22 40.49 SUM 2013 09 24 23 40.47 SUM 2013 09 25 00 40.51 SUM 2013 09 25 01 40.27 SUM 2013 09 25 02 40.07 SUM 2013 09 25 03 39.63 SUM 2013 09 25 04 39.32 SUM 2013 09 25 05 39.32 SUM 2013 09 25 06 39.13 SUM 2013 09 25 07 38.43 SUM 2013 09 25 08 38.31 SUM 2013 09 25 09 38.49 SUM 2013 09 25 10 38.60 SUM 2013 09 25 11 39.23 SUM 2013 09 25 12 39.44 SUM 2013 09 25 13 41.27 SUM 2013 09 25 14 43.50 SUM 2013 09 25 15 45.28 SUM 2013 09 25 16 46.32 SUM 2013 09 25 17 46.62 SUM 2013 09 25 18 46.29 SUM 2013 09 25 19 46.42 SUM 2013 09 25 20 46.71 SUM 2013 09 25 21 46.96 SUM 2013 09 25 22 46.99 SUM 2013 09 25 23 47.38 SUM 2013 09 26 00 46.55 SUM 2013 09 26 01 42.67 SUM 2013 09 26 02 40.81 SUM 2013 09 26 03 39.72 SUM 2013 09 26 04 39.21 SUM 2013 09 26 05 38.99 SUM 2013 09 26 06 38.25 SUM 2013 09 26 07 37.64 SUM 2013 09 26 08 37.31 SUM 2013 09 26 09 37.27 SUM 2013 09 26 10 36.99 SUM 2013 09 26 11 36.92 SUM 2013 09 26 12 36.72 SUM 2013 09 26 13 36.70 SUM 2013 09 26 14 36.75 SUM 2013 09 26 15 36.63 SUM 2013 09 26 16 36.67 SUM 2013 09 26 17 36.58 SUM 2013 09 26 18 36.58 SUM 2013 09 26 19 36.06 SUM 2013 09 26 20 36.49 SUM 2013 09 26 21 36.28 SUM 2013 09 26 22 38.43 SUM 2013 09 26 23 39.15 SUM 2013 09 27 00 41.14 SUM 2013 09 27 01 44.18 SUM 2013 09 27 02 44.14 SUM 2013 09 27 03 44.26 SUM 2013 09 27 04 44.56 SUM 2013 09 27 05 44.86 SUM 2013 09 27 06 44.82 SUM 2013 09 27 07 45.21 SUM 2013 09 27 08 45.16 SUM 2013 09 27 09 45.11 SUM 2013 09 27 10 45.78 SUM 2013 09 27 11 46.13 SUM 2013 09 27 12 45.66 SUM 2013 09 27 13 44.84 SUM 2013 09 27 14 44.43 SUM 2013 09 27 15 43.70 SUM 2013 09 27 16 43.12 SUM 2013 09 27 17 42.24 SUM 2013 09 27 18 42.58 SUM 2013 09 27 19 40.91 SUM 2013 09 27 20 41.47 SUM 2013 09 27 21 43.04 SUM 2013 09 27 22 43.62 SUM 2013 09 27 23 43.67 SUM 2013 09 28 00 43.64 SUM 2013 09 28 01 43.65 SUM 2013 09 28 02 43.65 SUM 2013 09 28 03 43.56 SUM 2013 09 28 04 43.36 SUM 2013 09 28 05 43.10 SUM 2013 09 28 06 43.03 SUM 2013 09 28 07 42.89 SUM 2013 09 28 08 42.74 SUM 2013 09 28 09 42.33 SUM 2013 09 28 10 42.12 SUM 2013 09 28 11 41.98 SUM 2013 09 28 12 41.68 SUM 2013 09 28 13 41.37 SUM 2013 09 28 14 40.64 SUM 2013 09 28 15 39.76 SUM 2013 09 28 16 38.75 SUM 2013 09 28 17 38.36 SUM 2013 09 28 18 38.40 SUM 2013 09 28 19 38.63 SUM 2013 09 28 20 38.34 SUM 2013 09 28 21 37.66 SUM 2013 09 28 22 37.82 SUM 2013 09 28 23 37.66 SUM 2013 09 29 00 37.73 SUM 2013 09 29 01 37.98 SUM 2013 09 29 02 38.19 SUM 2013 09 29 03 38.39 SUM 2013 09 29 04 38.70 SUM 2013 09 29 05 39.18 SUM 2013 09 29 06 39.34 SUM 2013 09 29 07 39.01 SUM 2013 09 29 08 38.96 SUM 2013 09 29 09 38.85 SUM 2013 09 29 10 38.12 SUM 2013 09 29 11 37.28 SUM 2013 09 29 12 35.85 SUM 2013 09 29 13 36.79 SUM 2013 09 29 14 37.91 SUM 2013 09 29 15 38.30 SUM 2013 09 29 16 38.82 SUM 2013 09 29 17 39.62 SUM 2013 09 29 18 40.68 SUM 2013 09 29 19 39.70 SUM 2013 09 29 20 39.88 SUM 2013 09 29 21 40.78 SUM 2013 09 29 22 41.16 SUM 2013 09 29 23 40.42 SUM 2013 09 30 00 42.15 SUM 2013 09 30 01 41.65 SUM 2013 09 30 02 40.82 SUM 2013 09 30 03 40.57 SUM 2013 09 30 04 40.55 SUM 2013 09 30 05 40.36 SUM 2013 09 30 06 40.10 SUM 2013 09 30 07 39.69 SUM 2013 09 30 08 39.51 SUM 2013 09 30 09 39.25 SUM 2013 09 30 10 38.88 SUM 2013 09 30 13 38.57 SUM 2013 09 30 14 39.18 SUM 2013 09 30 15 40.37 SUM 2013 09 30 16 42.12 SUM 2013 09 30 17 44.26 SUM 2013 09 30 18 46.83 SUM 2013 09 30 19 49.51 SUM 2013 09 30 20 50.00 SUM 2013 09 30 21 50.68 SUM 2013 09 30 22 50.67 SUM 2013 09 30 23 50.17