| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1 | 1.08 | 0.95 |
| 2024 | 1.16 | 1.43 | 0.96 |
| 2023 | 1.55 | 2.03 | 1.15 |
| 2022 | 1.07 | 1.47 | 0.81 |
| 2021 | 0.79 | 1.21 | 0.67 |
| 2020 | 0.75 | 0.86 | 0.68 |
| 2019 | 0.91 | 1.11 | 0.8 |
| 2018 | 0.97 | 1.1 | 0.82 |
| 2017 | 1.19 | 1.41 | 1.06 |
| 2016 | 1.22 | 1.68 | 1.11 |
| 2015 | 1.94 | 2.87 | 1.37 |
| 2014 | 1.14 | 1.77 | 1 |
| 2013 | 1.59 | 2.63 | 1.11 |
| 2012 | 1.53 | 2.43 | 1.34 |
| 2011 | 1.5 | 1.84 | 1.26 |
| 2010 | 1.99 | 2.32 | 1.62 |
| 2009 | 2.28 | 2.9 | 1.79 |
| 2008 | 2.37 | 4.61 | 1.58 |
| 2007 | 3.77 | 5.92 | 1.75 |
| 2006 | 1.39 | 1.79 | 1.19 |
| 2005 | 1.25 | 1.55 | 1.05 |
| 2004 | 2.4 | 3.93 | 1.22 |
| 2003 | 3.75 | 4.68 | 2.54 |
| 2002 | 4.26 | 5.81 | 3.4 |
| 2001 | 9.71 | 11.27 | 8.2 |
| 2000 | 8.69 | 11.84 | 5.05 |
| 1999 | 5.8 | 8.54 | 4.48 |
| 1998 | 4.93 | 6.57 | 3.37 |
| 1997 | 6.2 | 9.71 | 4.44 |