| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.77 | 2.21 | 1.6 |
| 2024 | 1.76 | 2.03 | 1.4 |
| 2023 | 1.94 | 2.38 | 1.66 |
| 2022 | 1.98 | 2.35 | 1.63 |
| 2021 | 2.24 | 3.15 | 1.79 |
| 2020 | 1.91 | 2.45 | 1.53 |
| 2019 | 1.74 | 2.33 | 1.33 |
| 2018 | 1.84 | 2.59 | 1.24 |
| 2017 | 2.93 | 3.74 | 2.28 |
| 2016 | 3.32 | 4.42 | 2.58 |
| 2015 | 3.84 | 5.95 | 2.45 |
| 2014 | 2.5 | 3.41 | 2.12 |
| 2013 | 3.9 | 6.54 | 2.32 |
| 2012 | 6.84 | 9.06 | 5.26 |
| 2011 | 9.79 | 12.83 | 5.5 |
| 2010 | 6.73 | 13.99 | 4.03 |
| 2009 | 5.04 | 7.89 | 2.31 |
| 2008 | 6.27 | 15.88 | 1.59 |
| 2007 | 12.66 | 23.84 | 4.32 |
| 2006 | 3.86 | 5.71 | 2.69 |
| 2005 | 2.53 | 3.07 | 2.08 |
| 2004 | 3.02 | 3.87 | 2.54 |
| 2003 | 2.67 | 3.24 | 2.37 |
| 2002 | 3.35 | 3.86 | 2.51 |
| 2001 | 4.66 | 5.67 | 3.39 |
| 2000 | 5.49 | 7.01 | 3.59 |
| 1999 | 7.82 | 15.27 | 3.21 |
| 1998 | 14.34 | 26.02 | 4.05 |