| Date | Value |
|---|---|
| Mar 11, 2015 23:53 | 490 ppm |
| Mar 3, 2015 18:20 | 450 ppm |
| Feb 19, 2015 19:19 | 460 ppm |
| Feb 15, 2015 23:51 | 430 ppm |
| Feb 8, 2015 02:25 | 445 ppm |
| Feb 4, 2015 20:56 | 425 ppm |
| Feb 1, 2015 23:23 | 410 ppm |
| Jan 28, 2015 23:47 | 440 ppm |
| Jan 27, 2015 00:26 | 415 ppm |
| Jan 25, 2015 01:32 | 395 ppm |
| Jan 24, 2015 00:35 | 375 ppm |