| Date | Value |
|---|---|
| May 5, 2019 12:12 | 1440 ppm |
| Oct 21, 2018 11:45 | 1260 ppm |
| Oct 10, 2018 09:41 | 1200 ppm |
| Aug 16, 2018 13:19 | 1200 ppm |
| Aug 1, 2018 11:32 | 1200 ppm |
| Nov 13, 2017 06:03 | 1226 ppm |
| Aug 7, 2017 06:31 | 1320 ppm |
| Jun 6, 2017 06:31 | 1306 ppm |
| Dec 3, 2016 06:31 | 1320 ppm |
| Oct 11, 2016 05:21 | 1380 ppm |