| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.58 | 1.93 | 1.32 |
| 2024 | 1.19 | 2.02 | 0.86 |
| 2023 | 1.44 | 1.62 | 1.25 |
| 2022 | 1.37 | 2.24 | 0.97 |
| 2021 | 0.97 | 1.44 | 0.85 |
| 2020 | 0.96 | 1.22 | 0.81 |
| 2019 | 1.04 | 1.43 | 0.82 |
| 2018 | 1.06 | 1.58 | 0.76 |
| 2017 | 1.89 | 2.44 | 1.34 |
| 2016 | 2.2 | 2.84 | 1.68 |
| 2015 | 2.52 | 4.13 | 1.45 |
| 2014 | 1.91 | 2.48 | 1.58 |
| 2013 | 1.59 | 1.93 | 1.32 |
| 2012 | 1.41 | 1.76 | 1.1 |
| 2011 | 2.3 | 3.24 | 1.49 |
| 2010 | 2.2 | 2.73 | 1.55 |
| 2009 | 1.71 | 2.3 | 1.03 |
| 2008 | 1.63 | 2.68 | 0.85 |
| 2007 | 2.43 | 3.31 | 1.37 |
| 2006 | 1.09 | 1.51 | 0.88 |
| 2005 | 0.75 | 1.09 | 0.5 |
| 2004 | 1.09 | 1.5 | 0.85 |
| 2003 | 1.49 | 1.83 | 1.05 |
| 2002 | 1.74 | 2.05 | 1.37 |
| 2001 | 2.19 | 2.73 | 1.55 |
| 2000 | 2.04 | 2.48 | 1.57 |
| 1999 | 1.7 | 2.08 | 1.45 |
| 1998 | 3.11 | 5.22 | 1.57 |
| 1997 | 5.8 | 9.99 | 3.83 |