| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.7 | 0.75 | 0.64 |
| 2024 | 0.65 | 0.77 | 0.54 |
| 2023 | 0.92 | 1.1 | 0.7 |
| 2022 | 1.16 | 1.42 | 0.97 |
| 2021 | 1.32 | 1.77 | 1.03 |
| 2020 | 1.53 | 2.45 | 1 |
| 2019 | 1.07 | 1.37 | 0.93 |
| 2018 | 1.29 | 1.75 | 0.93 |
| 2017 | 1.89 | 2.47 | 1.63 |
| 2016 | 1.93 | 2.57 | 1.73 |
| 2015 | 3.17 | 5.47 | 1.97 |
| 2014 | 1.96 | 2.81 | 1.59 |
| 2013 | 2.04 | 2.52 | 1.72 |
| 2012 | 2.25 | 2.91 | 1.69 |
| 2011 | 4.13 | 5.64 | 2.31 |
| 2010 | 3.51 | 5.68 | 2.4 |
| 2009 | 3.52 | 5 | 1.89 |
| 2008 | 3.04 | 5.98 | 1.28 |
| 2007 | 4.42 | 6.66 | 2.41 |
| 2006 | 2.82 | 4.94 | 2.12 |
| 2005 | 2.9 | 3.56 | 2.19 |
| 2004 | 3.84 | 5.88 | 2.57 |
| 2003 | 4.14 | 4.57 | 3.57 |