| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.95 | 1.05 | 0.88 |
| 2024 | 0.95 | 1.11 | 0.82 |
| 2023 | 1.14 | 1.34 | 0.97 |
| 2022 | 1.52 | 1.91 | 1.17 |
| 2021 | 1.29 | 2.67 | 0.86 |
| 2020 | 1.08 | 1.29 | 0.93 |
| 2019 | 1.22 | 1.61 | 1.02 |
| 2018 | 1.39 | 1.88 | 1.03 |
| 2017 | 1.97 | 2.45 | 1.64 |
| 2016 | 1.78 | 2.67 | 1.4 |
| 2015 | 2.39 | 4.29 | 1.49 |
| 2014 | 1.63 | 2.02 | 1.26 |
| 2013 | 2.1 | 3.3 | 1.58 |
| 2012 | 1.62 | 1.91 | 1.32 |
| 2011 | 1.84 | 2.09 | 1.51 |
| 2010 | 2.18 | 2.88 | 1.68 |
| 2009 | 2.59 | 3.36 | 2.03 |
| 2008 | 3.51 | 7.21 | 1.32 |
| 2007 | 4.31 | 5.74 | 2.47 |
| 2006 | 2.23 | 2.75 | 1.7 |
| 2005 | 2.14 | 2.78 | 1.66 |
| 2004 | 2.89 | 3.31 | 2.51 |
| 2003 | 2.53 | 3.18 | 2.1 |
| 2002 | 3.6 | 4.71 | 2.3 |
| 2001 | 4.34 | 5.14 | 2.85 |
| 2000 | 4.75 | 5.69 | 2.59 |
| 1999 | 4.01 | 5.58 | 3.2 |
| 1998 | 4.33 | 5.37 | 3.2 |