| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2021 | 31.75 | 47.34 | 17.89 |
| 2020 | 18.73 | 39.16 | 10.03 |
| 2019 | 13.51 | 15.96 | 11.46 |
| 2018 | 14.86 | 20.22 | 10.52 |
| 2017 | 15.46 | 17.94 | 12.89 |
| 2016 | 12.5 | 14.44 | 10.24 |
| 2015 | 14.41 | 19.22 | 10.33 |
| 2014 | 11.02 | 15.33 | 8.68 |
| 2013 | 10.68 | 13.97 | 8.6 |
| 2012 | 10.38 | 12.19 | 8.69 |
| 2011 | 15.26 | 23.33 | 8.09 |
| 2010 | 22.34 | 32.74 | 15.5 |
| 2009 | 22.76 | 33.88 | 13.04 |
| 2008 | 26.44 | 60.93 | 11.65 |
| 2007 | 54.3 | 87.04 | 36.84 |
| 2006 | 21.62 | 37.41 | 16.68 |
| 2005 | 15.94 | 17.95 | 13.64 |
| 2004 | 19.39 | 23.3 | 12.32 |
| 2003 | 19.54 | 22.22 | 17.09 |
| 2002 | 21.64 | 25.73 | 18.84 |
| 2001 | 26.71 | 33.15 | 18.89 |
| 2000 | 33.11 | 40.01 | 25.4 |
| 1999 | 26.22 | 37.35 | 19.97 |
| 1998 | 36.03 | 52.5 | 27.59 |
| 1997 | 42.76 | 58.95 | 23.54 |