| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 2.91 | 3.73 | 2.25 |
| 2024 | 2.15 | 3.3 | 1.63 |
| 2023 | 2.65 | 4.1 | 1.68 |
| 2022 | 1.89 | 2.74 | 1.47 |
| 2021 | 1.91 | 3 | 1.52 |
| 2020 | 2.43 | 3.99 | 1.6 |
| 2019 | 2.21 | 3.35 | 1.61 |
| 2018 | 1.88 | 2.47 | 1.38 |
| 2017 | 3.23 | 4.39 | 2.3 |
| 2016 | 4.03 | 5.08 | 2.79 |
| 2015 | 4.11 | 8.94 | 2.1 |
| 2014 | 2.07 | 2.39 | 1.67 |
| 2013 | 1.58 | 1.94 | 1.28 |
| 2012 | 1.71 | 2.23 | 1.26 |
| 2011 | 3.23 | 4.8 | 1.63 |
| 2010 | 3.42 | 5.13 | 2.53 |
| 2009 | 1.87 | 2.71 | 0.97 |
| 2008 | 1.62 | 2.87 | 0.7 |
| 2007 | 2.19 | 3.2 | 1.13 |
| 2006 | 1.09 | 1.32 | 0.87 |
| 2005 | 1.21 | 1.75 | 0.79 |
| 2004 | 1.84 | 2.41 | 1.47 |
| 2003 | 2.2 | 2.82 | 1.63 |
| 2002 | 4.32 | 4.82 | 3.58 |
| 2001 | 5.56 | 6.49 | 4.26 |
| 2000 | 5.92 | 6.94 | 5.1 |
| 1999 | 6.42 | 9.5 | 4.66 |
| 1998 | 5.8 | 7.02 | 4.34 |