| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 2.6 | 2.88 | 2.25 |
| 2024 | 2.14 | 3.2 | 1.51 |
| 2023 | 2.49 | 3.43 | 1.66 |
| 2022 | 1.86 | 2.66 | 1.4 |
| 2021 | 3.41 | 4.52 | 2.4 |
| 2020 | 4.53 | 6.03 | 2.93 |
| 2019 | 2.1 | 3.12 | 1.34 |
| 2018 | 1.84 | 2.97 | 1.23 |
| 2017 | 2.4 | 2.74 | 2.05 |
| 2016 | 2.72 | 3.28 | 2.19 |
| 2015 | 3.31 | 5.3 | 2.01 |
| 2014 | 2 | 2.47 | 1.52 |
| 2013 | 1.75 | 2.31 | 1.36 |
| 2012 | 1.75 | 2.19 | 1.33 |
| 2011 | 2.84 | 4.12 | 1.66 |
| 2010 | 4.01 | 5.56 | 2.97 |
| 2009 | 2.57 | 3.57 | 1.14 |
| 2008 | 2.34 | 4.89 | 0.97 |
| 2007 | 4.1 | 5 | 2.45 |
| 2006 | 2.47 | 3.03 | 2.11 |
| 2005 | 2.2 | 2.79 | 1.89 |
| 2004 | 3.46 | 4.7 | 2.66 |
| 2003 | 4.06 | 5.02 | 3.08 |
| 2002 | 3.97 | 5.13 | 2.71 |
| 2001 | 4.88 | 6.49 | 3.53 |
| 2000 | 8.3 | 11.09 | 6.48 |
| 1999 | 8.6 | 15.62 | 4.73 |
| 1998 | 13.21 | 18.63 | 9.52 |
| 1997 | 14.5 | 23.82 | 5.87 |