| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.01 | 1.12 | 0.96 |
| 2024 | 1.1 | 1.46 | 0.91 |
| 2023 | 1.28 | 1.68 | 1.11 |
| 2022 | 1.09 | 1.39 | 0.78 |
| 2021 | 1.09 | 1.35 | 0.95 |
| 2020 | 1.2 | 1.38 | 0.98 |
| 2019 | 1.15 | 1.36 | 0.97 |
| 2018 | 1.33 | 1.83 | 0.97 |
| 2017 | 2.42 | 3.53 | 1.07 |
| 2016 | 2.93 | 3.96 | 2.31 |
| 2015 | 3.12 | 4.7 | 2.11 |
| 2014 | 2.49 | 3.08 | 2.05 |
| 2013 | 2.24 | 2.85 | 1.73 |
| 2012 | 2.46 | 3.19 | 1.69 |
| 2011 | 4.53 | 6.53 | 2.74 |
| 2010 | 4.66 | 6.23 | 3.26 |
| 2009 | 4.09 | 5.63 | 2.23 |
| 2008 | 2.94 | 6 | 1.19 |
| 2007 | 5.38 | 6.91 | 3.65 |
| 2006 | 3.57 | 4.56 | 2.97 |
| 2005 | 2.58 | 2.96 | 1.42 |
| 2004 | 3.69 | 5.49 | 2.62 |