| Date | Value |
|---|---|
| Jul 21, 2018 22:28 | 500 ppm |
| Jul 14, 2018 18:29 | 540 ppm |
| Jun 7, 2018 11:58 | 440 ppm |
| Apr 15, 2018 19:53 | 425 ppm |
| Feb 4, 2018 22:11 | 405 ppm |
| Jan 25, 2018 20:22 | 445 ppm |
| Jan 23, 2018 22:42 | 425 ppm |
| Jan 13, 2018 16:13 | 395 ppm |
| Jan 4, 2018 20:02 | 400 ppm |
| Dec 17, 2017 12:54 | 400 ppm |
| Dec 13, 2017 21:00 | 400 ppm |
| Dec 10, 2017 09:52 | 440 ppm |
| Dec 9, 2017 22:37 | 400 ppm |
| Dec 9, 2017 19:35 | 380 ppm |
| Dec 6, 2017 18:21 | 375 ppm |