| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.62 | 0.65 | 0.59 |
| 2024 | 0.67 | 0.77 | 0.55 |
| 2023 | 0.64 | 0.71 | 0.59 |
| 2022 | 0.66 | 0.84 | 0.57 |
| 2021 | 0.98 | 1.59 | 0.73 |
| 2020 | 0.79 | 0.97 | 0.7 |
| 2019 | 0.94 | 1.27 | 0.78 |
| 2018 | 1.01 | 1.11 | 0.9 |
| 2017 | 1.22 | 1.43 | 1.06 |
| 2016 | 1.29 | 1.72 | 1.16 |
| 2015 | 2.1 | 3.85 | 1.47 |
| 2014 | 1.04 | 1.82 | 0.85 |
| 2013 | 0.98 | 1.11 | 0.86 |
| 2012 | 1.11 | 1.26 | 0.96 |
| 2011 | 1.42 | 1.78 | 1.12 |
| 2010 | 1.91 | 2.38 | 1.55 |
| 2009 | 2.21 | 2.75 | 1.64 |
| 2008 | 3.49 | 10.78 | 1.4 |
| 2007 | 4.88 | 10.4 | 2.26 |
| 2006 | 2.05 | 2.41 | 1.68 |
| 2005 | 2.07 | 2.53 | 1.64 |
| 2004 | 9.42 | 32.98 | 2.46 |
| 2003 | 24.23 | 30.06 | 11.63 |
| 2002 | 12.36 | 14.81 | 9.07 |
| 2001 | 11.61 | 14.19 | 8.34 |
| 2000 | 11.91 | 15.53 | 9.32 |
| 1999 | 8.89 | 12.8 | 6.56 |
| 1998 | 11.78 | 17.43 | 7.54 |
| 1997 | 15.42 | 26.67 | 9.42 |