| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.39 | 0.51 | 0.3 |
| 2023 | 0.69 | 0.93 | 0.48 |
| 2022 | 0.9 | 1.14 | 0.65 |
| 2021 | 1.33 | 1.92 | 0.9 |
| 2020 | 1.73 | 2.2 | 1.48 |
| 2019 | 2.04 | 2.43 | 1.77 |
| 2018 | 2.5 | 3.9 | 1.69 |
| 2017 | 2.36 | 3.21 | 1.79 |
| 2016 | 2.7 | 3.06 | 1.87 |
| 2015 | 1.87 | 3.04 | 1.6 |
| 2014 | 1.29 | 1.95 | 1.02 |
| 2013 | 1.75 | 2.47 | 1.26 |
| 2012 | 1.77 | 2.02 | 1.55 |
| 2011 | 1.99 | 2.48 | 1.66 |
| 2010 | 2.45 | 3.34 | 1.88 |
| 2009 | 3.47 | 4.86 | 2.4 |
| 2008 | 4.09 | 8.22 | 1.89 |
| 2007 | 9.1 | 15.57 | 4.77 |
| 2006 | 3.05 | 6.78 | 2.1 |
| 2005 | 1.75 | 2.43 | 1.27 |
| 2004 | 1.91 | 2.54 | 1.61 |
| 2003 | 1.96 | 2.41 | 1.52 |
| 2002 | 2.08 | 2.42 | 1.84 |
| 2001 | 2.55 | 2.84 | 2.19 |
| 2000 | 2.72 | 3.84 | 2.05 |
| 1999 | 2.09 | 3.14 | 1.54 |
| 1998 | 2.37 | 3.04 | 1.79 |
| 1997 | 3.53 | 5.02 | 2.1 |