| Date | Value |
|---|---|
| May 11, 2015 10:58 | 1 ppb |
| May 7, 2015 19:42 | 5 ppb |
| Apr 28, 2015 09:48 | 17 ppb |
| Apr 23, 2015 14:06 | 14 ppb |
| Apr 18, 2015 12:17 | 11 ppb |
| Dec 23, 2014 16:59 | 17 ppb |
| Dec 9, 2014 17:49 | 5 ppb |
| Dec 7, 2014 16:26 | 26 ppb |
| Nov 17, 2014 10:14 | 6 ppb |
| Nov 16, 2014 11:49 | 3 ppb |
| Nov 15, 2014 15:01 | 13 ppb |
| Nov 13, 2014 19:51 | 5 ppb |