| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.12 | 1.3 | 1.01 |
| 2024 | 0.94 | 1.1 | 0.81 |
| 2023 | 1.15 | 1.25 | 1.03 |
| 2022 | 1.31 | 1.68 | 1.1 |
| 2021 | 1.2 | 1.38 | 1.06 |
| 2020 | 1.3 | 1.71 | 1.05 |
| 2019 | 1.46 | 2.07 | 1.18 |
| 2018 | 1.65 | 2.23 | 1.12 |
| 2017 | 2.62 | 3.48 | 1.81 |
| 2016 | 1.96 | 2.44 | 1.62 |
| 2015 | 3.27 | 5.41 | 1.77 |
| 2014 | 2.22 | 4.49 | 1.54 |
| 2013 | 1.6 | 2.06 | 1.18 |
| 2012 | 1.8 | 2.19 | 1.48 |
| 2011 | 2.26 | 2.86 | 1.59 |
| 2010 | 2.86 | 3.59 | 2.35 |
| 2009 | 3.14 | 3.98 | 2.15 |
| 2008 | 4.03 | 7.69 | 1.65 |
| 2007 | 3.73 | 5.07 | 2.84 |
| 2006 | 2.17 | 3.09 | 1.57 |
| 2005 | 1.85 | 2.17 | 1.64 |
| 2004 | 2.08 | 2.32 | 1.68 |
| 2003 | 2.35 | 2.8 | 2.14 |
| 2002 | 2.62 | 2.96 | 1.83 |
| 2001 | 3.28 | 3.87 | 2.37 |
| 2000 | 3.96 | 4.76 | 3.28 |