| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 2.39 | 2.46 | 2.3 |
| 2024 | 2.18 | 2.51 | 1.71 |
| 2023 | 2 | 2.6 | 1.63 |
| 2022 | 2.53 | 3 | 2.28 |
| 2021 | 2.67 | 3.18 | 2.22 |
| 2020 | 2.31 | 2.62 | 1.93 |
| 2019 | 2.62 | 3.19 | 2.18 |
| 2018 | 2.82 | 3.84 | 2.21 |
| 2017 | 2.86 | 3.13 | 2.55 |
| 2016 | 2.51 | 2.82 | 2.28 |
| 2015 | 3.06 | 4.49 | 2.16 |
| 2014 | 2.31 | 3.23 | 1.95 |
| 2013 | 2.91 | 3.7 | 2.41 |
| 2012 | 3.41 | 4.47 | 2.59 |
| 2011 | 5.17 | 7.32 | 3.83 |
| 2010 | 7.41 | 10.72 | 5.76 |
| 2009 | 9.75 | 12.87 | 5.96 |
| 2008 | 8.81 | 15.03 | 5.6 |