| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0 | ||
| 2025 | 0 | ||
| 2024 | 1.01 | 1.45 | 0.28 |
| 2023 | 1.54 | 2.49 | 0.93 |
| 2022 | 3.1 | 4.53 | 2.26 |
| 2021 | 2.78 | 4.24 | 1.5 |
| 2020 | 3.11 | 6.03 | 1.83 |
| 2019 | 3.15 | 5.45 | 2.08 |
| 2018 | 3.77 | 4.78 | 2.08 |
| 2017 | 4.8 | 5.79 | 3.93 |
| 2016 | 6.18 | 8.26 | 4.98 |
| 2015 | 6.53 | 11.61 | 3.76 |
| 2014 | 3.9 | 4.9 | 2.83 |
| 2013 | 2.89 | 4.09 | 2.24 |
| 2012 | 3.37 | 4.66 | 2.07 |
| 2011 | 5.21 | 6.87 | 3.33 |
| 2010 | 7.15 | 10.27 | 5.01 |
| 2009 | 6.09 | 8.47 | 2.65 |
| 2008 | 3.28 | 5.26 | 1.42 |
| 2007 | 4.58 | 5.77 | 3.78 |