| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.99 | 1.25 | 0.9 |
| 2024 | 0.95 | 1.21 | 0.8 |
| 2023 | 1.34 | 2.01 | 0.97 |
| 2022 | 2.29 | 3.26 | 1.72 |
| 2021 | 2.66 | 3.53 | 2.02 |
| 2020 | 2.26 | 3.17 | 1.45 |
| 2019 | 1.75 | 2.59 | 1.37 |
| 2018 | 2.92 | 4.03 | 1.76 |
| 2017 | 3.33 | 4.07 | 2.71 |
| 2016 | 3.23 | 4.59 | 2.69 |
| 2015 | 3.39 | 5.99 | 2.22 |
| 2014 | 1.95 | 2.53 | 1.61 |
| 2013 | 2.13 | 2.69 | 1.64 |
| 2012 | 2.12 | 3.08 | 1.45 |
| 2011 | 5.63 | 8.76 | 2.66 |
| 2010 | 9.82 | 12.81 | 7.43 |
| 2009 | 9.8 | 13.11 | 5.82 |