| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.91 | 0.96 | 0.86 |
| 2024 | 1 | 1.23 | 0.83 |
| 2023 | 1.27 | 1.57 | 1 |
| 2022 | 1.63 | 1.99 | 1.31 |
| 2021 | 1.71 | 2.81 | 1.16 |
| 2020 | 1.17 | 1.55 | 0.91 |
| 2019 | 1.17 | 1.56 | 0.97 |
| 2018 | 1.36 | 1.86 | 0.98 |
| 2017 | 1.77 | 2.25 | 1.46 |
| 2016 | 1.46 | 1.71 | 1.16 |
| 2015 | 1.84 | 3.78 | 1.19 |
| 2014 | 1.07 | 1.48 | 0.86 |
| 2013 | 1.12 | 1.46 | 0.89 |
| 2012 | 1.58 | 2.22 | 1.05 |
| 2011 | 3.46 | 4.95 | 1.65 |
| 2010 | 3.5 | 4.46 | 2.35 |
| 2009 | 2.58 | 3.53 | 1.69 |
| 2008 | 5.11 | 15.19 | 1.2 |
| 2007 | 11.24 | 19.18 | 6.36 |
| 2006 | 5.36 | 8.08 | 2.23 |
| 2005 | 2.38 | 3.07 | 1.96 |
| 2004 | 3.07 | 4.06 | 2.33 |
| 2003 | 4.51 | 5.83 | 2.56 |
| 2002 | 6.21 | 7.14 | 5.09 |
| 2001 | 9.13 | 10.72 | 7.02 |
| 2000 | 7.63 | 11.92 | 5.37 |
| 1999 | 4.22 | 5.87 | 3.18 |
| 1998 | 3.69 | 4.52 | 2.79 |
| 1997 | 4.6 | 6.76 | 2.93 |