| Date | Value |
|---|---|
| Dec 22, 2014 15:15 | 20 ppm |
| Dec 14, 2014 14:40 | 20 ppm |
| Dec 7, 2014 08:48 | 20 ppm |
| Nov 30, 2014 05:16 | 20 ppm |
| Nov 25, 2014 09:18 | 32 ppm |
| Nov 15, 2014 08:12 | 12 ppm |
| Nov 1, 2014 14:52 | 12 ppm |
| Oct 29, 2014 14:14 | 12 ppm |
| Oct 26, 2014 17:23 | 16 ppm |
| Oct 17, 2014 04:28 | 12 ppm |
| Oct 13, 2014 10:32 | 10 ppm |
| Sep 30, 2014 15:16 | 12 ppm |
| Sep 7, 2014 05:25 | 4 ppm |
| Aug 17, 2014 10:17 | 2 ppm |
| Aug 14, 2014 15:10 | 2 ppm |