| Date | Value |
|---|---|
| May 11, 2015 19:05 | 425 ppm |
| Apr 28, 2015 09:50 | 395 ppm |
| Apr 23, 2015 15:09 | 450 ppm |
| Apr 20, 2015 14:07 | 385 ppm |
| Apr 19, 2015 10:29 | 375 ppm |
| Apr 18, 2015 12:51 | 350 ppm |
| Feb 21, 2015 13:41 | 596 ppm |
| Dec 7, 2014 17:25 | 415 ppm |
| Nov 17, 2014 13:46 | 406 ppm |
| Oct 9, 2014 19:54 | 405 ppm |