| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.63 | 0.7 | 0.52 |
| 2023 | 0.71 | 0.83 | 0.61 |
| 2022 | 0.69 | 0.84 | 0.59 |
| 2021 | 0.76 | 0.91 | 0.69 |
| 2020 | 0.84 | 1.05 | 0.75 |
| 2019 | 1.26 | 1.87 | 0.85 |
| 2018 | 2.35 | 3.18 | 1.61 |
| 2017 | 2.27 | 2.56 | 1.98 |
| 2016 | 1.77 | 2.23 | 1.36 |
| 2015 | 2.17 | 3.23 | 1.66 |
| 2014 | 1.86 | 2.38 | 1.53 |
| 2013 | 3.49 | 5.27 | 2.1 |
| 2012 | 2.67 | 4.31 | 1.85 |
| 2011 | 2.89 | 4.63 | 1.78 |
| 2010 | 2.56 | 3.8 | 1.71 |
| 2009 | 3.39 | 10.3 | 0.83 |
| 2008 | 0.81 | 1.27 | 0.36 |
| 2007 | 1.03 | 1.3 | 0.64 |
| 2006 | 0.64 | 0.75 | 0.52 |
| 2005 | 0.38 | 0.63 | 0.18 |
| 2004 | 0.35 | 0.67 | 0.19 |