| Date | Value |
|---|---|
| Jun 10, 2019 23:27 | 400 ppm |
| Jun 1, 2019 16:58 | 400 ppm |
| May 23, 2019 14:15 | 400 ppm |
| May 19, 2019 12:44 | 420 ppm |
| May 16, 2019 14:42 | 425 ppm |
| May 15, 2019 14:42 | 325 ppm |
| Sep 6, 2016 15:20 | 400 ppm |
| Sep 1, 2016 19:50 | 390 ppm |
| Aug 25, 2016 12:17 | 410 ppm |
| Aug 18, 2016 16:28 | 400 ppm |
| Aug 18, 2016 07:07 | 400 ppm |