| Date | Value |
|---|---|
| Aug 9, 2015 00:25 | 360 ppm |
| Apr 3, 2015 11:52 | 340 ppm |
| Mar 8, 2015 21:54 | 320 ppm |
| Feb 14, 2015 10:30 | 340 ppm |
| Feb 7, 2015 23:53 | 320 ppm |
| Dec 21, 2014 12:28 | 340 ppm |
| Dec 3, 2014 22:19 | 320 ppm |
| Nov 26, 2014 22:27 | 300 ppm |
| Oct 26, 2014 20:57 | 320 ppm |
| Sep 23, 2014 22:03 | 340 ppm |
| Sep 10, 2014 21:37 | 440 ppm |
| Sep 4, 2014 22:24 | 380 ppm |