| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1 | 1.06 | 0.9 |
| 2024 | 0.94 | 1.28 | 0.76 |
| 2023 | 1.11 | 1.23 | 0.99 |
| 2022 | 1.13 | 1.49 | 0.97 |
| 2021 | 1.26 | 1.69 | 1.13 |
| 2020 | 2.03 | 4.55 | 1.19 |
| 2019 | 1.37 | 1.96 | 1.09 |
| 2018 | 1.43 | 1.98 | 0.96 |
| 2017 | 2.34 | 3.04 | 1.8 |
| 2016 | 2.62 | 3.96 | 2.1 |
| 2015 | 5.16 | 8.9 | 3.02 |
| 2014 | 3.46 | 6.08 | 2.57 |
| 2013 | 2.92 | 3.72 | 2.4 |
| 2012 | 2.69 | 3.35 | 2.28 |
| 2011 | 4.31 | 5.28 | 2.64 |
| 2010 | 5.77 | 7.91 | 4.48 |
| 2009 | 5.54 | 6.96 | 4.08 |
| 2008 | 6.88 | 17.61 | 2.74 |
| 2007 | 13.34 | 21.08 | 3.8 |
| 2006 | 2.89 | 4.74 | 1.47 |
| 2005 | 2.08 | 2.97 | 1.43 |
| 2004 | 3.84 | 5.46 | 2.95 |
| 2003 | 4.34 | 4.98 | 3.6 |
| 2002 | 3.33 | 4.02 | 2.33 |
| 2001 | 7.54 | 9.28 | 6.25 |
| 2000 | 7.95 | 9.95 | 6.55 |
| 1999 | 9.16 | 15.09 | 6.78 |
| 1998 | 10.65 | 13.65 | 8.44 |
| 1997 | 7.09 | 11 | 3.55 |