| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2021 | 31.6 | 39.26 | 25.83 |
| 2020 | 33.01 | 60.8 | 23.39 |
| 2019 | 24.78 | 30.05 | 19.22 |
| 2018 | 30.26 | 38.64 | 21.13 |
| 2017 | 26.96 | 38.39 | 20.48 |
| 2016 | 18.97 | 21.34 | 16.5 |
| 2015 | 26.11 | 39.57 | 20.35 |
| 2014 | 22.23 | 28.57 | 19.65 |
| 2013 | 18.64 | 23.9 | 13.3 |
| 2012 | 16.92 | 22.86 | 12.9 |
| 2011 | 22 | 29.28 | 13.42 |
| 2010 | 13.43 | 28.61 | 7.7 |
| 2009 | 23.57 | 43.1 | 9.7 |
| 2008 | 26.34 | 60.47 | 8.9 |
| 2007 | 50.03 | 77.53 | 36.58 |
| 2006 | 29.52 | 43.37 | 17.83 |
| 2005 | 20.16 | 25.57 | 16.72 |
| 2004 | 17.94 | 27.44 | 6.92 |
| 2003 | 18.94 | 31.22 | 11.79 |
| 2002 | 37.31 | 44.64 | 25.9 |
| 2001 | 40.85 | 57.94 | 26.39 |
| 2000 | 61.04 | 72.97 | 45.53 |
| 1999 | 58.71 | 91.37 | 44.79 |