| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.13 | 1.36 | 0.98 |
| 2024 | 1.01 | 1.4 | 0.78 |
| 2023 | 0.85 | 1.01 | 0.66 |
| 2022 | 0.73 | 0.88 | 0.56 |
| 2021 | 0.92 | 1.16 | 0.72 |
| 2020 | 1 | 1.26 | 0.78 |
| 2019 | 1.12 | 1.55 | 0.85 |
| 2018 | 1.72 | 2.44 | 1.08 |
| 2017 | 3.1 | 4.94 | 2.19 |
| 2016 | 4.52 | 5.46 | 2.97 |
| 2015 | 4.78 | 6.48 | 2.57 |
| 2014 | 2.04 | 3.24 | 1.4 |
| 2013 | 1.43 | 1.71 | 1.24 |
| 2012 | 1.23 | 1.51 | 0.97 |
| 2011 | 1.97 | 3.03 | 1.05 |
| 2010 | 3.5 | 4.83 | 2.72 |
| 2009 | 3.74 | 5.42 | 2.52 |
| 2008 | 5.76 | 16.18 | 1.35 |
| 2007 | 13.35 | 21.16 | 7.47 |