| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.5 | 0.52 | 0.44 |
| 2024 | 0.46 | 0.61 | 0.39 |
| 2023 | 0.56 | 0.67 | 0.47 |
| 2022 | 0.52 | 0.58 | 0.43 |
| 2021 | 0.68 | 0.89 | 0.49 |
| 2020 | 0.85 | 1.17 | 0.68 |
| 2019 | 1 | 1.41 | 0.68 |
| 2018 | 1.37 | 2.14 | 0.86 |
| 2017 | 1.54 | 2.11 | 1.3 |
| 2016 | 1.43 | 1.79 | 1.01 |
| 2015 | 1.99 | 3.16 | 1.03 |
| 2014 | 1.36 | 1.71 | 1.03 |
| 2013 | 2.09 | 2.69 | 1.41 |
| 2012 | 2.42 | 3.06 | 1.83 |
| 2011 | 2.82 | 4.25 | 2 |
| 2010 | 2.63 | 4.2 | 1.67 |
| 2009 | 1.25 | 1.77 | 0.91 |
| 2008 | 1.18 | 1.79 | 0.62 |
| 2007 | 1.44 | 1.98 | 1.14 |