| Date | Value |
|---|---|
| Jul 8, 2015 12:07 | 412 ppm |
| May 9, 2015 07:16 | 425 ppm |
| Apr 19, 2015 14:51 | 409 ppm |
| Feb 14, 2015 06:26 | 355 ppm |
| Feb 11, 2015 04:59 | 380 ppm |
| Feb 7, 2015 14:23 | 334 ppm |
| Jan 29, 2015 14:19 | 400 ppm |
| Jan 16, 2015 11:25 | 370 ppm |
| Jan 2, 2015 13:57 | 370 ppm |
| Nov 23, 2014 12:02 | 345 ppm |
| Nov 21, 2014 11:46 | 384 ppm |
| Nov 15, 2014 12:27 | 353 ppm |