| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.97 | 1.01 | 0.9 |
| 2024 | 1.03 | 1.2 | 0.8 |
| 2023 | 1.33 | 1.76 | 1.01 |
| 2022 | 1 | 1.32 | 0.66 |
| 2021 | 0.83 | 1.36 | 0.53 |
| 2020 | 0.76 | 0.99 | 0.62 |
| 2019 | 0.62 | 0.76 | 0.47 |
| 2018 | 0.58 | 0.73 | 0.44 |
| 2017 | 0.92 | 1.3 | 0.67 |
| 2016 | 1.32 | 1.94 | 1.16 |
| 2015 | 2.55 | 3.99 | 1.54 |
| 2014 | 3.27 | 4.8 | 2.25 |
| 2013 | 2.59 | 3.6 | 1.86 |
| 2012 | 1.93 | 2.22 | 1.64 |
| 2011 | 2.66 | 3.42 | 2.01 |
| 2010 | 2.72 | 3.61 | 1.96 |
| 2009 | 2.55 | 3.31 | 1.9 |
| 2008 | 2.46 | 4.8 | 1.27 |
| 2007 | 2.97 | 4.42 | 1.51 |
| 2006 | 1.19 | 1.53 | 0.93 |
| 2005 | 1.26 | 1.55 | 0.84 |
| 2004 | 2.05 | 3.72 | 1.19 |