| Date | Value |
|---|---|
| Feb 21, 2022 17:48 | 7 ppm |
| Dec 7, 2021 11:02 | 8 ppm |
| Oct 10, 2021 19:43 | 5.4 ppm |
| Jun 7, 2021 13:03 | 5.2 ppm |
| Mar 21, 2021 16:31 | 5.9 ppm |
| Jan 21, 2021 16:42 | 5.3 ppm |
| Jul 2, 2020 18:59 | 7.1 ppm |
| Apr 14, 2020 18:56 | 10.2 ppm |
| Feb 10, 2020 14:42 | 6.7 ppm |
| Dec 5, 2019 10:57 | 8.2 ppm |
| Sep 24, 2019 17:12 | 2 ppm |