| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.01 | 1.15 | 0.95 |
| 2024 | 0.91 | 1.15 | 0.67 |
| 2023 | 0.83 | 0.98 | 0.72 |
| 2022 | 0.84 | 1.05 | 0.71 |
| 2021 | 0.99 | 1.44 | 0.82 |
| 2020 | 1.43 | 2.41 | 0.59 |
| 2019 | 0.82 | 1.16 | 0.59 |
| 2018 | 0.83 | 1.12 | 0.59 |
| 2017 | 1.59 | 2.18 | 1.05 |
| 2016 | 1.83 | 2.23 | 1.66 |
| 2015 | 2.8 | 4.75 | 1.81 |
| 2014 | 2.1 | 2.63 | 1.8 |
| 2013 | 1.76 | 2.22 | 1.46 |
| 2012 | 1.9 | 2.24 | 1.52 |
| 2011 | 3.09 | 3.88 | 1.79 |
| 2010 | 3.43 | 4.54 | 2.71 |
| 2009 | 3.14 | 3.94 | 2.25 |
| 2008 | 4.25 | 7.29 | 1.72 |
| 2007 | 5.07 | 8.21 | 1.89 |
| 2006 | 1.42 | 2.11 | 1 |
| 2005 | 1.31 | 1.58 | 0.94 |
| 2004 | 2.39 | 4.4 | 1.53 |