| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.73 | 0.91 | 0.64 |
| 2024 | 0.58 | 0.9 | 0.32 |
| 2023 | 0.55 | 0.8 | 0.39 |
| 2022 | 0.79 | 1.1 | 0.61 |
| 2021 | 0.57 | 0.93 | 0.36 |
| 2020 | 0.69 | 1.63 | 0.48 |
| 2019 | 0.75 | 0.94 | 0.65 |
| 2018 | 0.8 | 0.95 | 0.68 |
| 2017 | 1.11 | 1.31 | 0.91 |
| 2016 | 1.36 | 1.62 | 1.04 |
| 2015 | 2.49 | 4.28 | 1.42 |
| 2014 | 1.25 | 1.84 | 0.83 |
| 2013 | 0.96 | 1.18 | 0.84 |
| 2012 | 1.02 | 1.27 | 0.78 |
| 2011 | 1.25 | 1.51 | 0.96 |
| 2010 | 1.38 | 1.92 | 1.09 |
| 2009 | 1.06 | 1.46 | 0.74 |
| 2008 | 1.19 | 2.52 | 0.59 |
| 2007 | 2.27 | 3.3 | 1.18 |
| 2006 | 0.96 | 1.36 | 0.56 |
| 2005 | 0.79 | 1.17 | 0.54 |
| 2004 | 1.29 | 2.45 | 0.74 |