| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2021 | 4.6 | 5.09 | 3.97 |
| 2020 | 5.33 | 6.25 | 4.82 |
| 2019 | 6.38 | 7.96 | 5.08 |
| 2018 | 7.49 | 10.36 | 6.12 |
| 2017 | 9.14 | 10.5 | 8.06 |
| 2016 | 6.87 | 10.52 | 5.76 |
| 2015 | 9.14 | 15.26 | 6.15 |
| 2014 | 4.73 | 9.15 | 3.89 |
| 2013 | 6.31 | 8.5 | 5.02 |
| 2012 | 7.08 | 8.23 | 6.2 |
| 2011 | 10.75 | 14.3 | 7.06 |
| 2010 | 13.51 | 21.31 | 11.83 |