| Date | Value |
|---|---|
| Mar 18, 2016 23:28 | 410 ppm |
| Mar 16, 2016 07:10 | 410 ppm |
| Mar 2, 2016 05:53 | 400 ppm |
| Feb 28, 2016 06:21 | 380 ppm |
| Feb 5, 2016 02:55 | 390 ppm |
| Jan 25, 2016 03:37 | 360 ppm |
| Jan 20, 2016 03:01 | 370 ppm |
| Jan 16, 2016 21:31 | 340 ppm |
| Jan 9, 2016 19:12 | 310 ppm |
| Dec 30, 2015 23:16 | 360 ppm |
| Nov 22, 2015 01:08 | 350 ppm |