| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.86 | 2.1 | 1.66 |
| 2024 | 1.63 | 2.09 | 1.07 |
| 2023 | 2.12 | 2.59 | 1.79 |
| 2022 | 1.72 | 2.17 | 1.33 |
| 2021 | 1.78 | 2.2 | 1.51 |
| 2020 | 1.93 | 2.34 | 1.62 |
| 2019 | 2.09 | 2.87 | 1.78 |
| 2018 | 2.26 | 2.94 | 1.71 |
| 2017 | 2.15 | 2.44 | 1.9 |
| 2016 | 2.09 | 2.5 | 1.7 |
| 2015 | 2.63 | 3.96 | 1.75 |
| 2014 | 2.03 | 2.91 | 1.65 |
| 2013 | 2.5 | 3.48 | 1.86 |
| 2012 | 3.52 | 4.78 | 2.27 |
| 2011 | 7.82 | 16.8 | 4.28 |
| 2010 | 9.27 | 15.82 | 8.02 |
| 2009 | 5.69 | 9.47 | 3.6 |
| 2008 | 5.82 | 10.67 | 2.77 |
| 2007 | 7.94 | 10.62 | 4.37 |
| 2006 | 3.17 | 4.45 | 2.33 |
| 2005 | 2.18 | 2.94 | 1.55 |
| 2004 | 2.65 | 3.38 | 2.1 |
| 2003 | 3.37 | 4.42 | 2.54 |
| 2002 | 6.27 | 7.86 | 5.29 |
| 2001 | 9.37 | 12.78 | 6.2 |
| 2000 | 8.37 | 10.33 | 7 |
| 1999 | 8.43 | 11.89 | 5.99 |
| 1998 | 5.74 | 7.2 | 4.61 |
| 1997 | 5.5 | 7.87 | 4.05 |