| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.07 | 1.14 | 1 |
| 2024 | 1.27 | 1.52 | 1.04 |
| 2023 | 1.03 | 1.27 | 0.78 |
| 2022 | 0.8 | 1.02 | 0.59 |
| 2021 | 0.65 | 0.99 | 0.57 |
| 2020 | 0.69 | 0.82 | 0.62 |
| 2019 | 0.92 | 1.09 | 0.75 |
| 2018 | 0.83 | 0.91 | 0.7 |
| 2017 | 1.05 | 1.51 | 0.82 |
| 2016 | 1.48 | 1.73 | 1.19 |
| 2015 | 1.82 | 2.39 | 1.24 |
| 2014 | 1.16 | 1.91 | 0.96 |
| 2013 | 1.29 | 1.88 | 1.06 |
| 2012 | 1.22 | 1.52 | 0.99 |
| 2011 | 1.49 | 2.23 | 1.01 |
| 2010 | 1.56 | 1.96 | 1.18 |
| 2009 | 1.62 | 2.1 | 0.84 |
| 2008 | 1.76 | 4.74 | 0.66 |
| 2007 | 4.31 | 7.38 | 1.55 |
| 2006 | 1.08 | 1.49 | 0.77 |
| 2005 | 1.14 | 1.62 | 0.85 |
| 2004 | 2.26 | 3.48 | 1.59 |
| 2003 | 3.02 | 3.68 | 2.13 |
| 2002 | 2.53 | 2.83 | 1.98 |
| 2001 | 3.06 | 3.61 | 2.19 |
| 2000 | 2.7 | 3.43 | 1.82 |
| 1999 | 2.03 | 2.64 | 1.69 |
| 1998 | 2.7 | 3.53 | 1.9 |
| 1997 | 3.75 | 5.4 | 2.91 |