| Date | Value |
|---|---|
| Oct 5, 2016 12:49 | 470 ppm |
| Apr 27, 2016 15:38 | 450 ppm |
| Apr 1, 2016 12:19 | 460 ppm |
| Mar 19, 2016 18:57 | 430 ppm |
| Mar 13, 2016 17:26 | 400 ppm |
| Mar 11, 2016 19:04 | 410 ppm |
| Mar 10, 2016 19:44 | 380 ppm |
| Feb 13, 2015 05:14 | 470 ppm |
| Feb 3, 2015 10:29 | 485 ppm |