| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2020 | 0.53 | 0.62 | 0.45 |
| 2019 | 0.63 | 0.82 | 0.54 |
| 2018 | 0.77 | 1.18 | 0.5 |
| 2017 | 1.18 | 1.48 | 1.06 |
| 2016 | 1.06 | 1.2 | 0.92 |
| 2015 | 1.74 | 3.05 | 0.88 |
| 2014 | 1.34 | 3.16 | 0.84 |
| 2013 | 1.42 | 2.16 | 1.08 |
| 2012 | 1.92 | 2.37 | 1.47 |
| 2011 | 2.21 | 2.81 | 1.75 |
| 2010 | 2.36 | 3.37 | 1.67 |
| 2009 | 3.16 | 4.45 | 1.51 |
| 2008 | 3.05 | 7.57 | 1.17 |
| 2007 | 6.39 | 9.17 | 3.21 |
| 2006 | 2.19 | 3.68 | 1.48 |
| 2005 | 1.88 | 2.22 | 1.6 |
| 2004 | 2.95 | 4.51 | 1.81 |
| 2003 | 3.87 | 4.5 | 3.37 |
| 2002 | 4.88 | 5.33 | 3.87 |
| 2001 | 7.25 | 9.81 | 5.29 |
| 2000 | 4.32 | 6.13 | 2.86 |