| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.9 | 0.96 | 0.82 |
| 2024 | 0.79 | 1.09 | 0.59 |
| 2023 | 0.82 | 0.92 | 0.74 |
| 2022 | 0.82 | 1.03 | 0.69 |
| 2021 | 0.83 | 0.95 | 0.72 |
| 2020 | 0.88 | 1.12 | 0.75 |
| 2019 | 0.91 | 1.24 | 0.72 |
| 2018 | 0.83 | 0.97 | 0.65 |
| 2017 | 1.11 | 1.4 | 0.87 |
| 2016 | 1.18 | 1.71 | 0.94 |
| 2015 | 2.35 | 3.01 | 1.74 |
| 2014 | 1.75 | 2.91 | 1.38 |
| 2013 | 1.63 | 1.95 | 1.39 |
| 2012 | 1.78 | 2.25 | 1.38 |
| 2011 | 2.2 | 2.7 | 1.54 |
| 2010 | 2.35 | 4.47 | 1.09 |
| 2009 | 3.18 | 4.31 | 1.78 |
| 2008 | 3.25 | 6.45 | 1.44 |
| 2007 | 7 | 13.66 | 3.02 |
| 2006 | 1.89 | 3.09 | 1.11 |
| 2005 | 1.38 | 1.92 | 1.03 |
| 2004 | 3.13 | 4.84 | 1.57 |
| 2003 | 4.77 | 5.41 | 4.37 |
| 2002 | 5.23 | 5.71 | 4.64 |
| 2001 | 7.07 | 8.22 | 6.28 |
| 2000 | 6.22 | 7.31 | 3.89 |
| 1999 | 3.5 | 4.31 | 2.69 |