| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.52 | 0.67 | 0.38 |
| 2024 | 0.4 | 0.46 | 0.32 |
| 2023 | 0.56 | 0.67 | 0.44 |
| 2022 | 0.66 | 0.88 | 0.5 |
| 2021 | 1.34 | 2.23 | 0.76 |
| 2020 | 1.13 | 1.67 | 0.71 |
| 2019 | 0.59 | 0.84 | 0.49 |
| 2018 | 0.62 | 0.82 | 0.41 |
| 2017 | 0.94 | 1.28 | 0.68 |
| 2016 | 1.06 | 1.27 | 0.88 |
| 2015 | 1.45 | 2.7 | 1.02 |
| 2014 | 0.91 | 1.16 | 0.74 |
| 2013 | 1.2 | 1.56 | 0.92 |
| 2012 | 1.38 | 1.89 | 0.95 |
| 2011 | 2.09 | 2.74 | 1.49 |
| 2010 | 2.01 | 2.6 | 1.31 |
| 2009 | 1.87 | 2.69 | 0.86 |
| 2008 | 2.09 | 4.47 | 0.66 |
| 2007 | 4.21 | 5.96 | 2.26 |
| 2006 | 1.48 | 3.01 | 0.76 |
| 2005 | 0.84 | 1.02 | 0.66 |