| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.83 | 0.99 | 0.7 |
| 2023 | 0.83 | 0.92 | 0.76 |
| 2022 | 0.78 | 0.86 | 0.7 |
| 2021 | 0.8 | 0.9 | 0.7 |
| 2020 | 0.9 | 1.09 | 0.82 |
| 2019 | 1.12 | 1.27 | 1 |
| 2018 | 1.26 | 1.56 | 1.08 |
| 2017 | 1.33 | 1.49 | 1.16 |
| 2016 | 1.12 | 1.44 | 0.98 |
| 2015 | 1.89 | 2.63 | 1.37 |
| 2014 | 1.43 | 2.11 | 1.15 |
| 2013 | 1.49 | 1.84 | 1.14 |
| 2012 | 1.59 | 1.91 | 1.31 |
| 2011 | 2.39 | 3.52 | 1.8 |
| 2010 | 2.79 | 3.5 | 2.29 |
| 2009 | 3.18 | 3.96 | 2.7 |
| 2008 | 5.05 | 10.09 | 2.61 |
| 2007 | 6.95 | 10.22 | 4.81 |