| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.11 | 1.44 | 0.79 |
| 2024 | 0.81 | 1.27 | 0.67 |
| 2023 | 0.97 | 1.25 | 0.83 |
| 2022 | 0.85 | 1.11 | 0.72 |
| 2021 | 0.84 | 0.97 | 0.72 |
| 2020 | 1.22 | 1.8 | 0.96 |
| 2019 | 1.87 | 3.69 | 1.2 |
| 2018 | 1.72 | 2.37 | 1.18 |
| 2017 | 2.52 | 3 | 2.16 |
| 2016 | 3.1 | 3.93 | 2.67 |
| 2015 | 4.18 | 7.03 | 2.74 |
| 2014 | 1.55 | 2.88 | 1.07 |
| 2013 | 1.56 | 2.11 | 1.3 |
| 2012 | 1.72 | 2.12 | 1.5 |
| 2011 | 2.14 | 2.53 | 1.59 |
| 2010 | 3.01 | 6.14 | 2.05 |
| 2009 | 5.68 | 8.89 | 2.76 |
| 2008 | 4.37 | 8.52 | 1.94 |
| 2007 | 11.6 | 23 | 4.99 |
| 2006 | 3.93 | 5.63 | 2.37 |
| 2005 | 2.29 | 3.28 | 1.44 |
| 2004 | 3.84 | 5.85 | 2.86 |
| 2003 | 4.3 | 5.94 | 3.2 |
| 2002 | 4.97 | 7.1 | 3.04 |
| 2001 | 5.43 | 7.12 | 4.06 |
| 2000 | 4.28 | 5.78 | 2.39 |
| 1999 | 2.59 | 3.28 | 2.07 |
| 1998 | 2.96 | 3.69 | 2.17 |
| 1997 | 4.55 | 6.88 | 3.11 |