| Date | Value |
|---|---|
| Sep 12, 2019 14:22 | 1222 ppm |
| Jul 14, 2019 14:38 | 1227 ppm |
| May 12, 2019 13:21 | 1328 ppm |
| Feb 7, 2019 17:20 | 1350 ppm |
| Dec 24, 2018 13:56 | 1372 ppm |
| Nov 30, 2018 10:50 | 1450 ppm |
| Oct 28, 2018 16:17 | 1420 ppm |
| Sep 27, 2018 17:13 | 1440 ppm |
| Aug 24, 2018 15:29 | 1440 ppm |
| Dec 22, 2017 15:22 | 1440 ppm |
| Nov 12, 2017 15:59 | 1400 ppm |
| Sep 30, 2017 20:23 | 1600 ppm |
| Aug 31, 2017 13:41 | 1600 ppm |