| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2018 | 5.97 | 7.38 | 5.02 |
| 2017 | 6.63 | 7.15 | 5.82 |
| 2016 | 6.54 | 7.12 | 5.8 |
| 2015 | 6.08 | 7.41 | 4.57 |
| 2014 | 3.96 | 6.22 | 3.35 |
| 2013 | 4.46 | 5.58 | 3.43 |
| 2012 | 4.57 | 5.41 | 3.88 |
| 2011 | 6.61 | 7.93 | 5.71 |
| 2010 | 9.23 | 11.49 | 7.48 |
| 2009 | 11.86 | 16.29 | 5.85 |
| 2008 | 10.72 | 21.43 | 4.98 |
| 2007 | 30.50 | 47.26 | 16.5 |
| 2006 | 13.70 | 27.65 | 10.15 |