| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.95 | 2.42 | 1.68 |
| 2024 | 1.63 | 2.27 | 1.3 |
| 2023 | 2.37 | 3.13 | 1.99 |
| 2022 | 2.57 | 3.06 | 2.13 |
| 2021 | 2.89 | 4.2 | 2.36 |
| 2020 | 2.64 | 3.68 | 1.79 |
| 2019 | 2.5 | 3.61 | 1.36 |
| 2018 | 2.96 | 3.9 | 1.38 |
| 2017 | 3.85 | 5.63 | 2.27 |
| 2016 | 2.71 | 3.32 | 2.31 |
| 2015 | 3.09 | 5.24 | 2.01 |
| 2014 | 2.2 | 2.54 | 1.9 |
| 2013 | 2.7 | 5 | 1.8 |
| 2012 | 3.69 | 5.18 | 2.96 |
| 2011 | 6.13 | 7.85 | 3.7 |
| 2010 | 6.28 | 7.68 | 4.98 |
| 2009 | 4.71 | 6.56 | 2.07 |
| 2008 | 4 | 9.45 | 1.62 |
| 2007 | 7.55 | 12.05 | 3 |
| 2006 | 2.79 | 3.64 | 2 |
| 2005 | 2.25 | 2.77 | 1.87 |
| 2004 | 3.34 | 4.66 | 2.44 |
| 2003 | 4.07 | 4.61 | 3.5 |
| 2002 | 6.49 | 8.17 | 3.98 |
| 2001 | 6.84 | 8.45 | 4.81 |
| 2000 | 5.47 | 7.27 | 3.27 |
| 1999 | 4.04 | 8.03 | 2.91 |
| 1998 | 3.58 | 4.48 | 2.84 |
| 1997 | 3.22 | 4.47 | 2.43 |