| Date | Value |
|---|---|
| Jul 22, 2014 11:57 | 390 ppm |
| Jun 17, 2014 11:39 | 370 ppm |
| May 27, 2014 08:12 | 360 ppm |
| May 12, 2014 12:36 | 350 ppm |
| May 1, 2014 15:33 | 340 ppm |
| Apr 24, 2014 15:07 | 380 ppm |
| Apr 10, 2014 16:00 | 380 ppm |
| Apr 3, 2014 17:00 | 320 ppm |
| Mar 27, 2014 15:33 | 310 ppm |