| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.7 | 0.78 | 0.63 |
| 2024 | 0.8 | 0.98 | 0.64 |
| 2023 | 0.76 | 0.9 | 0.64 |
| 2022 | 0.86 | 1.08 | 0.75 |
| 2021 | 0.97 | 1.47 | 0.73 |
| 2020 | 0.7 | 0.86 | 0.61 |
| 2019 | 0.89 | 1.1 | 0.71 |
| 2018 | 0.96 | 1.17 | 0.82 |
| 2017 | 1.26 | 1.77 | 0.94 |
| 2016 | 1.11 | 1.61 | 0.86 |
| 2015 | 1.22 | 1.85 | 0.86 |
| 2014 | 0.89 | 1.38 | 0.74 |
| 2013 | 1.39 | 1.96 | 0.97 |
| 2012 | 2.04 | 2.57 | 1.51 |
| 2011 | 3.54 | 4.99 | 2.09 |
| 2010 | 4.47 | 6.64 | 2.86 |
| 2009 | 4.99 | 7.7 | 1.99 |
| 2008 | 5.54 | 10.48 | 1.42 |
| 2007 | 5.7 | 11.3 | 1.92 |
| 2006 | 1.6 | 2.06 | 1.32 |
| 2005 | 1.69 | 2.31 | 1.39 |