| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.94 | 1.2 | 0.77 |
| 2024 | 0.75 | 1.05 | 0.51 |
| 2023 | 0.73 | 1.03 | 0.55 |
| 2022 | 0.69 | 0.88 | 0.47 |
| 2021 | 0.74 | 1.24 | 0.61 |
| 2020 | 0.75 | 0.94 | 0.59 |
| 2019 | 0.77 | 0.94 | 0.6 |
| 2018 | 0.84 | 1.26 | 0.57 |
| 2017 | 1.72 | 2.29 | 1.08 |
| 2016 | 2.24 | 3.2 | 1.34 |
| 2015 | 1.99 | 3.03 | 1.3 |
| 2014 | 1.66 | 2.04 | 1.43 |
| 2013 | 2.23 | 3.45 | 1.48 |
| 2012 | 3.44 | 4.1 | 2.64 |
| 2011 | 5.46 | 9.24 | 2.66 |
| 2010 | 7.3 | 10.37 | 4.67 |
| 2009 | 7.78 | 11.45 | 2.97 |
| 2008 | 4.41 | 8.41 | 2.19 |