| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2021 | 17.19 | 18.97 | 15.39 |
| 2020 | 17.43 | 23.23 | 14.08 |
| 2019 | 21.89 | 35.18 | 16.79 |
| 2018 | 19.56 | 24.83 | 15.15 |
| 2017 | 23.34 | 27.95 | 19.76 |
| 2016 | 21.08 | 33.52 | 18.23 |
| 2015 | 32.11 | 39.75 | 16.63 |
| 2014 | 18.57 | 27.23 | 15.14 |
| 2013 | 15.14 | 20.18 | 11.72 |
| 2012 | 16.02 | 21.64 | 12.84 |
| 2011 | 19.34 | 23.71 | 16.66 |
| 2010 | 23.77 | 35.2 | 16.74 |
| 2009 | 30.68 | 38.3 | 24.69 |
| 2008 | 25.3 | 37.92 | 15.45 |