| Date | Value |
|---|---|
| Nov 9, 2018 08:25 | 1340 ppm |
| Oct 5, 2018 11:09 | 1340 ppm |
| Sep 28, 2018 12:51 | 1500 ppm |
| Feb 26, 2018 01:29 | 1260 ppm |
| Feb 25, 2017 12:47 | 1560 ppm |
| Feb 17, 2017 07:18 | 1620 ppm |
| Feb 1, 2017 07:16 | 1320 ppm |
| Jan 6, 2017 09:56 | 1320 ppm |
| Dec 25, 2016 01:58 | 1400 ppm |