| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.65 | 0.68 | 0.61 |
| 2024 | 0.62 | 0.72 | 0.51 |
| 2023 | 0.52 | 0.59 | 0.46 |
| 2022 | 0.48 | 0.53 | 0.44 |
| 2021 | 0.5 | 0.55 | 0.47 |
| 2020 | 0.54 | 0.62 | 0.5 |
| 2019 | 0.66 | 0.76 | 0.6 |
| 2018 | 0.71 | 0.87 | 0.6 |
| 2017 | 0.88 | 1 | 0.81 |
| 2016 | 0.84 | 1.01 | 0.77 |
| 2015 | 1.1 | 1.78 | 0.85 |
| 2014 | 0.64 | 1.05 | 0.54 |
| 2013 | 0.67 | 0.82 | 0.56 |
| 2012 | 0.83 | 0.99 | 0.67 |
| 2011 | 1.17 | 1.5 | 0.89 |
| 2010 | 1.82 | 2.84 | 1.42 |
| 2009 | 1.87 | 2.64 | 1.33 |
| 2008 | 2.19 | 3.94 | 1.3 |
| 2007 | 2.99 | 3.95 | 2.05 |
| 2006 | 1.86 | 2.45 | 1.03 |
| 2005 | 1.89 | 2.16 | 1.52 |
| 2004 | 1.63 | 2.1 | 0.81 |
| 2003 | 1.51 | 1.98 | 1.29 |
| 2002 | 1.89 | 2.12 | 1.67 |
| 2001 | 2.43 | 2.88 | 1.74 |