| Date | Value |
|---|---|
| Feb 21, 2019 09:26 | 0.06 ppm |
| Jan 26, 2019 12:51 | 0.04 ppm |
| Dec 18, 2018 15:02 | 0.04 ppm |
| Dec 16, 2018 14:01 | 0.04 ppm |
| Dec 15, 2018 13:37 | 0.00 ppm |
| Oct 27, 2017 13:01 | 0.00 ppm |
| Mar 13, 2016 14:47 | 0.01 ppm |
| Jun 21, 2015 14:44 | 0.04 ppm |
| Mar 21, 2015 10:23 | 0.03 ppm |
| Feb 12, 2015 10:06 | 0.03 ppm |