| Date | Value |
|---|---|
| Dec 5, 2014 21:04 | 400 ppm |
| Sep 4, 2013 23:08 | 360 ppm |
| Jul 30, 2013 21:39 | 350 ppm |
| Mar 23, 2013 21:02 | 380 ppm |
| Feb 28, 2013 18:07 | 370 ppm |
| Feb 6, 2013 23:08 | 390 ppm |
| Jan 24, 2013 19:49 | 380 ppm |
| Dec 6, 2012 20:37 | 400 ppm |
| Nov 29, 2012 20:19 | 410 ppm |
| Nov 21, 2012 23:06 | 390 ppm |
| Nov 14, 2012 21:14 | 390 ppm |
| Nov 9, 2012 00:30 | 400 ppm |
| Nov 5, 2012 20:44 | 380 ppm |