| Date | Value |
|---|---|
| Jul 13, 2014 21:57 | 375 ppm |
| Jun 14, 2014 18:24 | 375 ppm |
| May 24, 2014 18:20 | 380 ppm |
| May 17, 2014 21:21 | 380 ppm |
| Apr 21, 2014 20:24 | 400 ppm |
| Apr 13, 2014 23:06 | 400 ppm |
| Mar 22, 2014 21:15 | 395 ppm |
| Mar 8, 2014 15:08 | 398 ppm |
| Mar 1, 2014 14:54 | 380 ppm |
| Feb 26, 2014 21:44 | 380 ppm |
| Feb 22, 2014 16:08 | 370 ppm |
| May 11, 2013 19:14 | 400 ppm |
| Feb 10, 2013 12:03 | 400 ppm |
| Dec 2, 2012 20:04 | 400 ppm |