| Date | Value |
|---|---|
| Mar 28, 2015 14:01 | 0.40 ppm |
| Oct 24, 2013 21:48 | 0.08 ppm |
| Oct 15, 2013 14:18 | 0.08 ppm |
| Oct 10, 2013 00:00 | 0.12 ppm |
| Sep 14, 2013 00:00 | 0.08 ppm |
| Aug 30, 2013 00:00 | 0.25 ppm |
| Aug 18, 2013 00:00 | 0.20 ppm |
| Aug 3, 2013 00:00 | 0.10 ppm |
| Jul 26, 2013 00:00 | 0.05 ppm |
| Jul 13, 2013 00:00 | 0.16 ppm |
| Jul 10, 2013 00:00 | 0.04 ppm |