| Date | Value |
|---|---|
| Dec 24, 2015 18:58 | 395 ppm |
| May 10, 2015 13:59 | 460 ppm |
| Jan 11, 2015 12:35 | 405 ppm |
| Jan 4, 2015 15:50 | 425 ppm |
| Dec 15, 2014 21:42 | 420 ppm |
| Dec 11, 2014 20:13 | 400 ppm |
| Nov 30, 2014 21:32 | 450 ppm |
| Nov 29, 2014 16:31 | 405 ppm |
| Nov 19, 2014 11:11 | 415 ppm |
| Nov 6, 2014 21:44 | 410 ppm |
| Nov 2, 2014 11:21 | 360 ppm |
| Oct 21, 2014 20:14 | 340 ppm |
| Sep 5, 2014 12:15 | 455 ppm |
| Aug 28, 2014 19:15 | 370 ppm |