| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2020 | 18.43 | 22.03 | 15.98 |
| 2019 | 16.95 | 18.92 | 14.95 |
| 2018 | 15.75 | 17.39 | 13.95 |
| 2017 | 15.68 | 17.01 | 14.23 |
| 2016 | 20.28 | 27.02 | 14.91 |
| 2015 | 17.45 | 19.97 | 14.01 |
| 2014 | 11.86 | 16.63 | 9.91 |
| 2013 | 11.4 | 12.77 | 10.07 |
| 2012 | 13.77 | 15.51 | 10.35 |
| 2011 | 14.37 | 17.51 | 11.18 |
| 2010 | 29.56 | 37.97 | 15.7 |
| 2009 | 30.62 | 35.13 | 26.71 |
| 2008 | 27.87 | 33.74 | 18.87 |
| 2007 | 34.47 | 46.09 | 24.23 |
| 2006 | 17.15 | 24.73 | 14.73 |
| 2005 | 20.62 | 23.59 | 17.44 |
| 2004 | 34.11 | 51.15 | 25.66 |