| Date | Value |
|---|---|
| Jun 14, 2014 22:52 | 430 ppm |
| Jun 12, 2014 23:18 | 425 ppm |
| Jun 9, 2014 22:41 | 440 ppm |
| Jun 3, 2014 16:12 | 430 ppm |
| May 31, 2014 11:50 | 440 ppm |
| May 30, 2014 21:26 | 430 ppm |
| May 28, 2014 21:54 | 400 ppm |
| May 25, 2014 11:35 | 425 ppm |
| May 23, 2014 19:30 | 415 ppm |
| May 20, 2014 22:05 | 420 ppm |
| May 19, 2014 22:26 | 400 ppm |