| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.92 | 1.2 | 0.7 |
| 2023 | 0.69 | 0.92 | 0.57 |
| 2022 | 0.78 | 1.17 | 0.6 |
| 2021 | 1.05 | 1.49 | 0.8 |
| 2020 | 0.62 | 1.14 | 0.42 |
| 2019 | 0.5 | 0.67 | 0.41 |
| 2018 | 0.61 | 0.83 | 0.52 |
| 2017 | 0.68 | 0.89 | 0.56 |
| 2016 | 0.53 | 0.67 | 0.49 |
| 2015 | 0.87 | 1.41 | 0.58 |
| 2014 | 0.62 | 0.98 | 0.45 |
| 2013 | 0.77 | 0.93 | 0.63 |
| 2012 | 0.97 | 1.29 | 0.67 |
| 2011 | 1.71 | 2.56 | 1.01 |
| 2010 | 2.15 | 3.65 | 1.23 |
| 2009 | 2.81 | 4.07 | 1.16 |
| 2008 | 2.98 | 7.18 | 0.95 |