| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2020 | 18.31 | 21.87 | 14.83 |
| 2019 | 19.82 | 24.31 | 16.57 |
| 2018 | 24.52 | 31.86 | 15.81 |
| 2017 | 22.43 | 28.16 | 17.79 |
| 2016 | 18.8 | 20.93 | 17.26 |
| 2015 | 19.99 | 25.54 | 15.82 |
| 2014 | 12.55 | 19.15 | 7.14 |
| 2013 | 10.28 | 18.74 | 6.86 |
| 2012 | 28.62 | 40.77 | 15.91 |
| 2011 | 43.37 | 55.85 | 30.53 |
| 2010 | 50.79 | 66.71 | 38.03 |