| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.3 | 0.32 | 0.28 |
| 2024 | 0.27 | 0.33 | 0.22 |
| 2023 | 0.33 | 0.4 | 0.26 |
| 2022 | 0.35 | 0.48 | 0.29 |
| 2021 | 0.54 | 0.68 | 0.42 |
| 2020 | 0.62 | 0.77 | 0.52 |
| 2019 | 0.81 | 1.08 | 0.66 |
| 2018 | 1 | 1.53 | 0.66 |
| 2017 | 1.5 | 1.87 | 1.26 |
| 2016 | 1.42 | 1.87 | 1.01 |
| 2015 | 1.33 | 2.71 | 0.66 |
| 2014 | 0.64 | 0.82 | 0.48 |
| 2013 | 0.93 | 1.15 | 0.8 |
| 2012 | 1.05 | 1.89 | 0.69 |
| 2011 | 2.65 | 3.81 | 1.4 |
| 2010 | 3.26 | 4.68 | 2.24 |
| 2009 | 3.09 | 4.73 | 1.06 |
| 2008 | 2.06 | 4.44 | 0.78 |
| 2007 | 3.61 | 6.01 | 2.12 |
| 2006 | 1.68 | 2.78 | 0.66 |
| 2005 | 0.7 | 0.87 | 0.47 |
| 2004 | 0.77 | 1.4 | 0.5 |