| Date | Value |
|---|---|
| Dec 9, 2018 09:28 | 65 ppm |
| Sep 1, 2017 10:05 | 0.80 ppm |
| Apr 20, 2017 19:12 | 0.00 ppm |
| Jan 9, 2017 11:03 | 0.10 ppm |
| Dec 7, 2016 09:20 | 0.30 ppm |
| Nov 28, 2016 12:21 | 0.00 ppm |
| Nov 17, 2016 16:58 | 0.00 ppm |
| Nov 13, 2016 15:40 | 0.00 ppm |
| Sep 8, 2016 15:59 | 1.2 ppm |