| Date | Value |
|---|---|
| Dec 14, 2016 00:35 | 440 ppm |
| Jun 15, 2016 00:36 | 456 ppm |
| Jun 7, 2016 04:15 | 450 ppm |
| Apr 25, 2016 02:31 | 455 ppm |
| Oct 3, 2015 00:23 | 350 ppm |
| Jul 24, 2015 22:16 | 375 ppm |
| Jul 12, 2015 01:59 | 410 ppm |
| Jul 7, 2015 01:05 | 410 ppm |
| Jun 16, 2015 02:41 | 386 ppm |
| May 19, 2015 00:11 | 380 ppm |
| Feb 24, 2015 00:05 | 366 ppm |