| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.5 | 0.56 | 0.44 |
| 2024 | 0.47 | 0.59 | 0.34 |
| 2023 | 0.66 | 0.81 | 0.53 |
| 2022 | 0.95 | 1.91 | 0.7 |
| 2021 | 0.82 | 1.11 | 0.69 |
| 2020 | 0.98 | 1.18 | 0.75 |
| 2019 | 0.85 | 1.06 | 0.71 |
| 2018 | 0.85 | 0.98 | 0.75 |
| 2017 | 1.11 | 1.37 | 0.9 |
| 2016 | 1.44 | 2.3 | 1.19 |
| 2015 | 2.03 | 3.97 | 1.26 |
| 2014 | 1.06 | 1.47 | 0.87 |
| 2013 | 1.12 | 1.53 | 0.84 |
| 2012 | 1.25 | 1.56 | 0.98 |
| 2011 | 1.89 | 2.47 | 1.05 |
| 2010 | 2.51 | 3.49 | 1.95 |
| 2009 | 2.85 | 7.04 | 1.81 |
| 2008 | 2.39 | 3.74 | 1.14 |
| 2007 | 2.96 | 4.41 | 1.79 |
| 2006 | 1.66 | 2.03 | 1.3 |
| 2005 | 1.92 | 2.8 | 1.08 |
| 2004 | 3.27 | 4.39 | 2.04 |
| 2003 | 3.03 | 3.47 | 2.46 |