| Date | Value |
|---|---|
| Aug 21, 2017 10:01 | 1360 ppm |
| Dec 14, 2016 09:51 | 1360 ppm |
| Nov 11, 2016 08:47 | 1440 ppm |
| Sep 30, 2016 13:48 | 1400 ppm |
| Jul 18, 2016 10:40 | 1340 ppm |
| Apr 5, 2016 09:59 | 1420 ppm |
| Feb 27, 2016 16:01 | 1300 ppm |
| Jan 9, 2016 16:56 | 1280 ppm |
| Dec 12, 2015 16:09 | 1280 ppm |