| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.55 | 0.58 | 0.51 |
| 2024 | 0.64 | 0.78 | 0.56 |
| 2023 | 0.56 | 0.69 | 0.42 |
| 2022 | 0.46 | 0.62 | 0.37 |
| 2021 | 0.52 | 0.67 | 0.43 |
| 2020 | 0.6 | 0.69 | 0.54 |
| 2019 | 0.69 | 0.79 | 0.55 |
| 2018 | 0.66 | 0.81 | 0.53 |
| 2017 | 1 | 1.41 | 0.75 |
| 2016 | 1.25 | 1.55 | 0.86 |
| 2015 | 1.27 | 1.78 | 0.84 |
| 2014 | 0.6 | 1.02 | 0.47 |
| 2013 | 0.79 | 1.08 | 0.65 |
| 2012 | 0.81 | 0.99 | 0.63 |
| 2011 | 1.45 | 2.26 | 0.81 |
| 2010 | 1.81 | 2.54 | 1.36 |
| 2009 | 2.13 | 2.81 | 1.14 |
| 2008 | 2.35 | 5.73 | 0.89 |
| 2007 | 4.87 | 8.18 | 1.68 |
| 2006 | 1.14 | 1.61 | 0.81 |
| 2005 | 1.08 | 1.43 | 0.9 |
| 2004 | 2.11 | 3.97 | 1.2 |