| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2020 | 6.65 | 7.44 | 5.76 |
| 2019 | 7.42 | 9.22 | 6.27 |
| 2018 | 8.44 | 10.72 | 6.68 |
| 2017 | 11.71 | 13.76 | 9.81 |
| 2016 | 11 | 14.19 | 9.12 |
| 2015 | 18.64 | 29.46 | 12.87 |
| 2014 | 6.38 | 17.73 | 4.57 |
| 2013 | 7.05 | 9.97 | 5.44 |
| 2012 | 7.6 | 9.16 | 6.32 |
| 2011 | 14.57 | 20.63 | 6.48 |
| 2010 | 16.39 | 22.88 | 11.61 |
| 2009 | 27.95 | 35.33 | 21.68 |