| Date | Value |
|---|---|
| Feb 8, 2014 22:37 | 1320 ppm |
| Nov 20, 2013 06:19 | 1200 ppm |
| Aug 14, 2013 07:49 | 1260 ppm |
| Jul 29, 2013 06:34 | 1260 ppm |
| Jul 3, 2013 06:35 | 1290 ppm |
| Jun 24, 2013 07:43 | 1350 ppm |
| Feb 28, 2013 06:13 | 1320 ppm |
| Feb 18, 2013 06:20 | 1350 ppm |
| Jan 20, 2013 07:29 | 1300 ppm |