| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.55 | 0.61 | 0.48 |
| 2024 | 0.61 | 0.83 | 0.37 |
| 2023 | 0.73 | 0.96 | 0.53 |
| 2022 | 0.71 | 1.06 | 0.51 |
| 2021 | 1 | 1.33 | 0.75 |
| 2020 | 0.83 | 0.96 | 0.72 |
| 2019 | 1.04 | 1.4 | 0.84 |
| 2018 | 1.07 | 1.37 | 0.78 |
| 2017 | 1.63 | 2.04 | 1.14 |
| 2016 | 1.7 | 2.44 | 1.23 |
| 2015 | 1.59 | 2.14 | 1.06 |
| 2014 | 0.97 | 1.92 | 0.74 |
| 2013 | 1.13 | 1.95 | 0.81 |
| 2012 | 1.76 | 2.11 | 1.43 |
| 2011 | 2.34 | 3.23 | 1.48 |
| 2010 | 3.68 | 5.28 | 2.95 |
| 2009 | 5.37 | 7.77 | 3.73 |
| 2008 | 6.46 | 10.01 | 3.49 |
| 2007 | 6.84 | 10.13 | 3.77 |
| 2006 | 4.3 | 8.02 | 2.72 |
| 2005 | 3.62 | 5.5 | 1.86 |
| 2004 | 1.91 | 3.04 | 1.33 |