| Date | Value |
|---|---|
| Feb 13, 2018 05:57 | 1350 ppm |
| Nov 15, 2017 21:47 | 1240 ppm |
| Aug 25, 2017 20:16 | 1120 ppm |
| Jul 18, 2017 21:46 | 1080 ppm |
| Apr 24, 2017 21:04 | 1400 ppm |
| Apr 4, 2017 20:06 | 1360 ppm |
| Mar 16, 2017 19:27 | 1480 ppm |
| Mar 7, 2017 20:42 | 1200 ppm |
| Feb 28, 2017 21:50 | 1440 ppm |
| Feb 23, 2017 21:13 | 1280 ppm |
| Feb 20, 2017 21:43 | 1300 ppm |
| Feb 15, 2017 22:20 | 1120 ppm |
| Feb 11, 2017 15:45 | 1100 ppm |
| Feb 3, 2017 12:07 | 1150 ppm |