| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.69 | 0.7 | 0.67 |
| 2024 | 0.79 | 1.03 | 0.62 |
| 2023 | 1.17 | 1.37 | 1 |
| 2022 | 1.79 | 2.97 | 1.16 |
| 2021 | 1.8 | 2.88 | 1.3 |
| 2020 | 1.84 | 2.57 | 1.33 |
| 2019 | 1.4 | 1.98 | 1.25 |
| 2018 | 1.53 | 1.98 | 1.27 |
| 2017 | 2.58 | 3.44 | 1.88 |
| 2016 | 3.01 | 4.29 | 2.57 |
| 2015 | 3.96 | 8.11 | 2.04 |
| 2014 | 1.74 | 2.26 | 1.37 |
| 2013 | 1.65 | 2.15 | 1.35 |
| 2012 | 2.52 | 3.85 | 1.84 |
| 2011 | 3.02 | 3.95 | 2.31 |
| 2010 | 2.71 | 4.14 | 1.99 |
| 2009 | 2.18 | 2.8 | 1.49 |
| 2008 | 1.79 | 3.44 | 0.93 |