| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2021 | 6.3 | 6.8 | 5.65 |
| 2020 | 7.27 | 9.18 | 6.09 |
| 2019 | 8.47 | 10.47 | 7.42 |
| 2018 | 10.27 | 16.32 | 7.69 |
| 2017 | 9.33 | 12.36 | 8.26 |
| 2016 | 8.34 | 10 | 7.06 |
| 2015 | 8.99 | 13.17 | 5.77 |
| 2014 | 5.6 | 9.5 | 4.68 |
| 2013 | 9.48 | 14.82 | 6.16 |
| 2012 | 11.79 | 14.58 | 9.48 |
| 2011 | 11.8 | 17.18 | 8.33 |
| 2010 | 16.82 | 27.95 | 12.36 |
| 2009 | 30.71 | 46.5 | 16.87 |
| 2008 | 32.21 | 107.1 | 12.2 |
| 2007 | 91.26 | 147.21 | 24.56 |