| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2020 | 5.25 | 6.06 | 4.73 |
| 2019 | 5.87 | 6.5 | 5.12 |
| 2018 | 5.92 | 7.38 | 5.02 |
| 2017 | 6.67 | 7.21 | 5.89 |
| 2016 | 6.64 | 7.23 | 6.19 |
| 2015 | 6.45 | 7.59 | 4.79 |
| 2014 | 4.39 | 6.38 | 3.89 |
| 2013 | 5.16 | 6.72 | 3.99 |
| 2012 | 5.44 | 7.45 | 4.09 |
| 2011 | 8.7 | 11.28 | 6.42 |
| 2010 | 12.15 | 15.66 | 9.24 |
| 2009 | 12.51 | 17 | 6.77 |
| 2008 | 20.63 | 55.62 | 5.82 |
| 2007 | 42.6 | 58.71 | 28.64 |
| 2006 | 16.76 | 29.3 | 12.12 |
| 2005 | 14.93 | 17.02 | 12.51 |
| 2004 | 21.75 | 31.96 | 14.63 |
| 2003 | 32.02 | 40.73 | 22.21 |
| 2002 | 37.07 | 43.99 | 27.77 |
| 2001 | 47.48 | 54.18 | 36.35 |
| 2000 | 59.07 | 67.17 | 52.18 |