| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0 | ||
| 2024 | 0.32 | 0.55 | 0.1 |
| 2023 | 0.48 | 0.64 | 0.4 |
| 2022 | 0.45 | 0.55 | 0.35 |
| 2021 | 0.44 | 0.54 | 0.34 |
| 2020 | 0.55 | 0.73 | 0.44 |
| 2019 | 0.9 | 1.31 | 0.55 |
| 2018 | 1.36 | 2.43 | 0.77 |
| 2017 | 2.34 | 2.77 | 2 |
| 2016 | 3.07 | 5.73 | 1.8 |
| 2015 | 4.04 | 6.09 | 2.76 |
| 2014 | 3.36 | 4.07 | 2.72 |
| 2013 | 15.46 | 37.53 | 2.63 |
| 2012 | 17.92 | 22.7 | 11.31 |
| 2011 | 25.29 | 30.8 | 17.93 |
| 2010 | 19.72 | 29.23 | 13.07 |
| 2009 | 11.75 | 17.6 | 6.63 |
| 2008 | 9.12 | 15.35 | 4.15 |
| 2007 | 12.02 | 17.3 | 5.72 |
| 2006 | 3.67 | 6.81 | 1.27 |
| 2005 | 1.68 | 2.23 | 1.09 |
| 2004 | 2.89 | 4.08 | 2.1 |
| 2003 | 3.6 | 4.62 | 2.55 |
| 2002 | 5.61 | 6.37 | 3.99 |
| 2001 | 7.06 | 8.72 | 5.53 |
| 2000 | 7.73 | 9.57 | 5.84 |
| 1999 | 5.51 | 7.75 | 3.41 |
| 1998 | 3.96 | 5.86 | 2.92 |
| 1997 | 3.14 | 4.78 | 1.92 |