| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.7 | 0.77 | 0.65 |
| 2024 | 0.65 | 0.77 | 0.58 |
| 2023 | 0.66 | 0.76 | 0.62 |
| 2022 | 0.68 | 0.76 | 0.6 |
| 2021 | 0.66 | 0.73 | 0.61 |
| 2020 | 0.7 | 0.83 | 0.61 |
| 2019 | 0.83 | 1.03 | 0.73 |
| 2018 | 0.96 | 1.17 | 0.7 |
| 2017 | 1.25 | 1.41 | 1.12 |
| 2016 | 1.3 | 1.83 | 1.18 |
| 2015 | 2.03 | 3.37 | 1.3 |
| 2014 | 0.97 | 1.54 | 0.76 |
| 2013 | 0.93 | 1.09 | 0.76 |
| 2012 | 1.17 | 1.55 | 0.97 |
| 2011 | 1.89 | 2.7 | 1.11 |
| 2010 | 2.37 | 3.11 | 1.89 |
| 2009 | 2.77 | 3.57 | 1.86 |
| 2008 | 3.2 | 5.09 | 1.68 |
| 2007 | 3.22 | 4.53 | 2.27 |