| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2021 | 5.65 | 6.4 | 4.85 |
| 2020 | 4.76 | 5.25 | 4.42 |
| 2019 | 5.2 | 5.82 | 4.73 |
| 2018 | 5.56 | 7.05 | 4.73 |
| 2017 | 6.41 | 7.21 | 5.82 |
| 2016 | 7.16 | 7.66 | 6.49 |
| 2015 | 7.35 | 8.65 | 6.02 |
| 2014 | 5.13 | 8.12 | 4.61 |
| 2013 | 6.82 | 9.4 | 5.1 |
| 2012 | 5.74 | 6.88 | 4.69 |
| 2011 | 7.75 | 9.71 | 5.97 |
| 2010 | 12.43 | 19.01 | 8.98 |
| 2009 | 14.25 | 20.88 | 7.13 |
| 2008 | 18.12 | 41.83 | 6.87 |
| 2007 | 39.9 | 60.37 | 27.49 |
| 2006 | 16.5 | 32 | 11.54 |
| 2005 | 14.02 | 16.63 | 10.47 |
| 2004 | 24.08 | 59.43 | 14.65 |
| 2003 | 31 | 40.93 | 21.5 |
| 2002 | 42.71 | 51.74 | 28.74 |
| 2001 | 59.74 | 77.57 | 50.07 |