| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.08 | 1.15 | 1.03 |
| 2024 | 1.11 | 1.21 | 0.97 |
| 2023 | 1.09 | 1.27 | 0.85 |
| 2022 | 0.86 | 0.94 | 0.77 |
| 2021 | 0.84 | 0.92 | 0.76 |
| 2020 | 0.88 | 0.99 | 0.82 |
| 2019 | 0.99 | 1.22 | 0.89 |
| 2018 | 1.03 | 1.26 | 0.85 |
| 2017 | 1.5 | 2.36 | 1.16 |
| 2016 | 1.12 | 1.48 | 0.69 |
| 2015 | 1.08 | 1.47 | 0.63 |
| 2014 | 0.89 | 1.58 | 0.69 |
| 2013 | 0.77 | 1.05 | 0.59 |
| 2012 | 0.82 | 0.94 | 0.7 |
| 2011 | 1.12 | 1.36 | 0.83 |
| 2010 | 1.64 | 2.49 | 1.22 |
| 2009 | 1.91 | 2.3 | 1.52 |
| 2008 | 7.42 | 15.44 | 1.41 |
| 2007 | 13.17 | 19.4 | 5.86 |
| 2006 | 4.48 | 6.03 | 2.95 |
| 2005 | 4.38 | 5.9 | 2.93 |
| 2004 | 5.02 | 7.16 | 2.42 |