| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.82 | 1.99 | 1.67 |
| 2024 | 1.86 | 2.23 | 1.61 |
| 2023 | 2.13 | 2.52 | 1.69 |
| 2022 | 1.87 | 2.28 | 1.56 |
| 2021 | 1.65 | 1.99 | 1.42 |
| 2020 | 1.47 | 1.74 | 1.27 |
| 2019 | 1.7 | 2.19 | 1.48 |
| 2018 | 2.11 | 2.57 | 1.59 |
| 2017 | 3.21 | 4.13 | 2.4 |
| 2016 | 3.93 | 4.6 | 3.1 |
| 2015 | 4.08 | 5.53 | 2.97 |
| 2014 | 2.9 | 3.36 | 2.35 |
| 2013 | 2.84 | 3.54 | 2.34 |
| 2012 | 3.75 | 4.65 | 2.67 |
| 2011 | 5.4 | 6.68 | 3.86 |
| 2010 | 7.32 | 9.2 | 5.61 |
| 2009 | 6.36 | 7.18 | 5.43 |
| 2008 | 7.88 | 12.79 | 4.42 |
| 2007 | 11.66 | 18.7 | 6.25 |
| 2006 | 4.56 | 6.53 | 2.7 |
| 2005 | 2.55 | 3.81 | 1.9 |
| 2004 | 2.03 | 2.53 | 1.72 |
| 2003 | 2.16 | 2.54 | 1.71 |
| 2002 | 3.1 | 3.42 | 2.56 |
| 2001 | 3.88 | 4.55 | 2.84 |
| 2000 | 3.75 | 4.28 | 3.22 |
| 1999 | 2.91 | 3.64 | 2.14 |
| 1998 | 2.83 | 3.6 | 2.06 |