| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.77 | 0.81 | 0.71 |
| 2024 | 0.68 | 0.98 | 0.55 |
| 2023 | 0.88 | 1.08 | 0.77 |
| 2022 | 0.86 | 1.08 | 0.74 |
| 2021 | 0.89 | 1.26 | 0.74 |
| 2020 | 1.03 | 1.36 | 0.73 |
| 2019 | 1.3 | 2 | 1.02 |
| 2018 | 1.67 | 2.12 | 1.22 |
| 2017 | 2.59 | 3.16 | 1.92 |
| 2016 | 2.15 | 2.82 | 1.54 |
| 2015 | 2.54 | 3.68 | 1.54 |
| 2014 | 2.34 | 2.91 | 1.72 |
| 2013 | 1.91 | 2.65 | 1.43 |
| 2012 | 1.63 | 2.03 | 1.27 |
| 2011 | 1.74 | 2.01 | 1.26 |
| 2010 | 2.47 | 3.77 | 1.72 |
| 2009 | 2.91 | 3.72 | 2.12 |
| 2008 | 3.48 | 6.57 | 1.67 |
| 2007 | 4.63 | 7.3 | 1.39 |
| 2006 | 1.23 | 1.5 | 1.06 |
| 2005 | 1.09 | 1.54 | 0.83 |
| 2004 | 1.61 | 2.16 | 1.2 |
| 2003 | 2.07 | 2.64 | 1.57 |
| 2002 | 3.41 | 4.58 | 2.77 |
| 2001 | 5.11 | 6.51 | 3.34 |
| 2000 | 6.06 | 7.59 | 5.08 |
| 1999 | 5.17 | 7.25 | 4.09 |
| 1998 | 6.22 | 8.78 | 4.85 |
| 1997 | 7.54 | 11.15 | 4.5 |