| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.55 | 0.65 | 0.49 |
| 2024 | 0.46 | 0.63 | 0.34 |
| 2023 | 0.58 | 0.69 | 0.49 |
| 2022 | 0.57 | 0.84 | 0.41 |
| 2021 | 0.5 | 0.67 | 0.45 |
| 2020 | 0.56 | 0.78 | 0.39 |
| 2019 | 0.5 | 0.65 | 0.43 |
| 2018 | 0.78 | 1.42 | 0.44 |
| 2017 | 1.9 | 2.7 | 1.25 |
| 2016 | 2.08 | 2.62 | 1.43 |
| 2015 | 2.13 | 3.8 | 1.12 |
| 2014 | 0.9 | 1.28 | 0.58 |
| 2013 | 0.7 | 0.95 | 0.57 |
| 2012 | 0.95 | 1.24 | 0.67 |
| 2011 | 1.92 | 3.06 | 1.01 |
| 2010 | 3.47 | 5.36 | 2.46 |
| 2009 | 3.29 | 5.31 | 1.75 |
| 2008 | 2.77 | 5.7 | 1.19 |
| 2007 | 5.23 | 7.5 | 3.71 |