| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.84 | 1.04 | 0.78 |
| 2024 | 0.82 | 0.92 | 0.69 |
| 2023 | 0.91 | 1.1 | 0.73 |
| 2022 | 0.95 | 1.14 | 0.75 |
| 2021 | 0.81 | 1.14 | 0.69 |
| 2020 | 0.83 | 0.93 | 0.75 |
| 2019 | 0.92 | 1.05 | 0.85 |
| 2018 | 0.99 | 1.16 | 0.87 |
| 2017 | 1.31 | 2.2 | 1.11 |
| 2016 | 1.35 | 1.83 | 1.16 |
| 2015 | 2.04 | 2.94 | 1.61 |
| 2014 | 1.29 | 2.23 | 1.09 |
| 2013 | 2.47 | 6.1 | 1.29 |
| 2012 | 1.99 | 4.71 | 1.58 |
| 2011 | 2.48 | 3.76 | 1.66 |
| 2010 | 2.94 | 3.77 | 2.23 |
| 2009 | 3.16 | 3.95 | 1.93 |
| 2008 | 3.53 | 6.92 | 1.4 |
| 2007 | 4.66 | 7.13 | 1.84 |
| 2006 | 1.85 | 2.25 | 1.59 |
| 2005 | 2.06 | 2.7 | 1.53 |
| 2004 | 3.07 | 4.03 | 2.3 |
| 2003 | 3.48 | 4.17 | 2.73 |