| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.67 | 0.71 | 0.6 |
| 2024 | 0.68 | 0.82 | 0.56 |
| 2023 | 1 | 1.26 | 0.74 |
| 2022 | 1.03 | 1.25 | 0.7 |
| 2021 | 1.24 | 1.63 | 0.86 |
| 2020 | 1.64 | 2.18 | 1.34 |
| 2019 | 1.9 | 2.65 | 1.38 |
| 2018 | 2.53 | 3.98 | 1.61 |
| 2017 | 2.95 | 3.93 | 2.46 |
| 2016 | 3.08 | 3.71 | 2.5 |
| 2015 | 5.69 | 9.55 | 2.75 |
| 2014 | 4.47 | 5.67 | 3.36 |
| 2013 | 6.99 | 9.05 | 4.74 |
| 2012 | 9.62 | 14.96 | 6.44 |
| 2011 | 15.77 | 22.66 | 11.6 |
| 2010 | 12.93 | 22.41 | 7.81 |
| 2009 | 5.87 | 8.29 | 4.38 |
| 2008 | 6.02 | 10.24 | 3.01 |
| 2007 | 7.73 | 10.63 | 6.08 |