| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.99 | 1.07 | 0.86 |
| 2024 | 0.67 | 0.97 | 0.52 |
| 2023 | 0.75 | 0.81 | 0.69 |
| 2022 | 0.83 | 1.11 | 0.64 |
| 2021 | 1 | 1.65 | 0.7 |
| 2020 | 0.77 | 0.89 | 0.69 |
| 2019 | 0.9 | 1.16 | 0.71 |
| 2018 | 1.2 | 1.63 | 0.93 |
| 2017 | 1.44 | 2.07 | 1.12 |
| 2016 | 1.1 | 1.27 | 0.9 |
| 2015 | 1.45 | 2.38 | 1.04 |
| 2014 | 0.67 | 1.46 | 0.51 |
| 2013 | 0.61 | 0.71 | 0.53 |
| 2012 | 0.66 | 0.79 | 0.56 |
| 2011 | 0.94 | 1.18 | 0.7 |
| 2010 | 1.1 | 1.5 | 0.9 |
| 2009 | 1.39 | 2.15 | 1 |
| 2008 | 1.77 | 3.57 | 0.86 |
| 2007 | 2.64 | 4.62 | 1.6 |
| 2006 | 1.02 | 1.49 | 0.8 |
| 2005 | 0.89 | 1.19 | 0.67 |
| 2004 | 1.5 | 2.43 | 1.06 |
| 2003 | 1.53 | 1.82 | 1.32 |
| 2002 | 1.44 | 1.59 | 1.29 |
| 2001 | 1.55 | 1.84 | 1.28 |
| 2000 | 1.62 | 2.48 | 1.03 |
| 1999 | 1.3 | 1.73 | 0.99 |
| 1998 | 1.25 | 1.56 | 0.9 |
| 1997 | 1.6 | 2.15 | 1.26 |