| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.32 | 1.49 | 1.2 |
| 2024 | 1.19 | 1.48 | 1 |
| 2023 | 1.64 | 1.84 | 1.38 |
| 2022 | 2.01 | 2.7 | 1.6 |
| 2021 | 1.84 | 2.15 | 1.62 |
| 2020 | 1.79 | 2.39 | 1.51 |
| 2019 | 1.98 | 2.41 | 1.68 |
| 2018 | 1.99 | 2.39 | 1.56 |
| 2017 | 2.66 | 4.06 | 1.91 |
| 2016 | 3.35 | 4.25 | 2.41 |
| 2015 | 4.37 | 7.95 | 2.35 |
| 2014 | 2.63 | 4.31 | 1.95 |
| 2013 | 3.26 | 4.4 | 2.43 |
| 2012 | 3.59 | 5.16 | 2.88 |
| 2011 | 5.62 | 7.42 | 3.68 |
| 2010 | 5.66 | 7.15 | 4.33 |
| 2009 | 4.32 | 6.21 | 2.24 |
| 2008 | 4.12 | 8.51 | 1.74 |
| 2007 | 6.67 | 10.39 | 2.98 |
| 2006 | 2.12 | 3.5 | 1.8 |
| 2005 | 2.43 | 3.71 | 1.7 |
| 2004 | 4.42 | 6.34 | 3.18 |
| 2003 | 5.86 | 7.42 | 4.13 |
| 2002 | 5.05 | 5.97 | 3.87 |
| 2001 | 5.68 | 6.55 | 4.52 |
| 2000 | 5.53 | 6.37 | 3.5 |
| 1999 | 4.39 | 6.33 | 2.99 |
| 1998 | 4.78 | 6.86 | 3.56 |
| 1997 | 4.39 | 7 | 3.03 |