| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2018 | 15.94 | 17.39 | 14.15 |
| 2017 | 14.56 | 17.01 | 12.5 |
| 2016 | 12.65 | 14.98 | 9.05 |
| 2015 | 18.62 | 21.57 | 13.32 |
| 2014 | 9.69 | 15.4 | 7.77 |
| 2013 | 12.66 | 14.22 | 11.3 |
| 2012 | 10.45 | 11.19 | 9.82 |
| 2011 | 15.32 | 17.91 | 12.96 |
| 2010 | 16.54 | 18.48 | 15.05 |
| 2009 | 29.15 | 33.66 | 26.09 |
| 2008 | 35.91 | 48.68 | 27.23 |
| 2007 | 26.60 | 39.14 | 14.58 |