| Date | Value |
|---|---|
| Mar 10, 2019 12:30 | 465 ppm |
| Jan 28, 2019 12:28 | 450 ppm |
| Jan 28, 2019 12:16 | 450 ppm |
| Nov 17, 2018 12:17 | 460 ppm |
| Nov 13, 2018 13:14 | 475 ppm |
| Nov 12, 2018 17:25 | 465 ppm |
| Oct 25, 2018 13:22 | 460 ppm |
| Sep 23, 2018 17:21 | 450 ppm |
| Sep 10, 2018 02:47 | 350 ppm |