| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2018 | 33.18 | 42.05 | 23.14 |
| 2017 | 25.43 | 31.01 | 19.63 |
| 2016 | 23.10 | 25.4 | 19.51 |
| 2015 | 27.56 | 34.69 | 20.1 |
| 2014 | 29.57 | 35.89 | 23.98 |
| 2013 | 31.20 | 35.51 | 25.43 |
| 2012 | 27.66 | 33.81 | 20.22 |
| 2011 | 31.21 | 39.48 | 25.93 |
| 2010 | 35.22 | 50.89 | 24.16 |
| 2009 | 15.80 | 22.65 | 11.81 |
| 2008 | 32.18 | 46.65 | 16.89 |
| 2007 | 30.98 | 46.37 | 12.16 |