| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.77 | 0.96 | 0.62 |
| 2024 | 0.65 | 1.17 | 0.39 |
| 2023 | 0.74 | 0.89 | 0.65 |
| 2022 | 0.72 | 0.85 | 0.61 |
| 2021 | 0.86 | 1.13 | 0.68 |
| 2020 | 1.34 | 1.71 | 1.13 |
| 2019 | 1.67 | 2.09 | 1.46 |
| 2018 | 2.04 | 3.08 | 1.31 |
| 2017 | 2.71 | 3.77 | 2.11 |
| 2016 | 6.87 | 22.16 | 2.39 |
| 2015 | 9.35 | 16.05 | 3.6 |
| 2014 | 2.72 | 3.6 | 2.12 |
| 2013 | 2.68 | 3.44 | 2.23 |
| 2012 | 2.91 | 3.35 | 2.54 |
| 2011 | 3.76 | 5.04 | 2.56 |
| 2010 | 4.79 | 6.11 | 3.39 |
| 2009 | 2.74 | 3.68 | 1.54 |
| 2008 | 4.8 | 12.49 | 1.22 |
| 2007 | 6.56 | 10.87 | 2.51 |
| 2006 | 2.37 | 3.45 | 1.71 |
| 2005 | 2.19 | 2.87 | 1.54 |
| 2004 | 3.58 | 4.86 | 2.68 |
| 2003 | 6.47 | 11.7 | 3.13 |
| 2002 | 12.84 | 17.52 | 10.88 |
| 2001 | 14.4 | 16.14 | 10.64 |
| 2000 | 11.94 | 15.19 | 7.09 |
| 1999 | 4.91 | 8.2 | 2.41 |
| 1998 | 7.89 | 9.52 | 6.35 |
| 1997 | 6.6 | 9.59 | 5.05 |