| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2020 | 31.75 | 33.26 | 30.44 |
| 2019 | 28.17 | 36.99 | 15.57 |
| 2018 | 25.68 | 40.27 | 15.11 |
| 2017 | 26.51 | 36.06 | 19.71 |
| 2016 | 18.07 | 21.01 | 14.88 |
| 2015 | 17.55 | 23.03 | 13.84 |
| 2014 | 9.66 | 14.79 | 5.95 |
| 2013 | 8 | 11.95 | 5.79 |
| 2012 | 17.81 | 24.37 | 10.1 |
| 2011 | 26.69 | 30.47 | 20.88 |
| 2010 | 33.47 | 48.34 | 25.5 |
| 2009 | 36.92 | 48.49 | 29.97 |
| 2008 | 55.11 | 120.42 | 26.31 |
| 2007 | 85.38 | 129.56 | 59.64 |
| 2006 | 34.05 | 59.51 | 19.86 |
| 2005 | 22.89 | 26.06 | 19.27 |
| 2004 | 23.02 | 29.85 | 19.61 |
| 2003 | 20.71 | 23.71 | 18.58 |
| 2002 | 21.43 | 25.28 | 18.7 |
| 2001 | 22.73 | 26.78 | 13.39 |
| 2000 | 22.38 | 26.79 | 18.92 |
| 1999 | 22.88 | 30.23 | 16.49 |