| Date | Value |
|---|---|
| Jul 29, 2019 11:46 | 2 ppm |
| Jul 22, 2019 20:52 | 2 ppm |
| Jul 1, 2019 19:33 | 1 ppm |
| Jun 23, 2019 09:45 | 1.2 ppm |
| Jun 19, 2019 21:36 | 0.75 ppm |
| Jun 14, 2019 14:15 | 1.2 ppm |
| Jun 9, 2019 09:50 | 2.5 ppm |
| Jun 5, 2019 09:48 | 4 ppm |
| May 25, 2019 07:28 | 1.2 ppm |
| May 6, 2019 07:54 | 1 ppm |