| Date | Value |
|---|---|
| Mar 10, 2014 21:27 | 0.04 ppm |
| Mar 2, 2014 20:55 | 0.04 ppm |
| Feb 25, 2014 20:34 | 0.05 ppm |
| Feb 10, 2014 16:48 | 0.02 ppm |
| Jan 25, 2014 07:44 | 0.04 ppm |
| Jan 19, 2014 13:51 | 0.02 ppm |
| Jan 17, 2014 21:07 | 0.03 ppm |
| Jan 7, 2014 15:19 | 0.03 ppm |
| Jan 6, 2013 17:33 | 0.02 ppm |