| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.61 | 0.65 | 0.55 |
| 2024 | 0.62 | 0.69 | 0.5 |
| 2023 | 0.68 | 0.78 | 0.61 |
| 2022 | 0.86 | 1.15 | 0.62 |
| 2021 | 1.1 | 2.01 | 0.62 |
| 2020 | 0.64 | 0.76 | 0.58 |
| 2019 | 0.8 | 1.09 | 0.68 |
| 2018 | 1.18 | 1.67 | 0.8 |
| 2017 | 1.21 | 1.5 | 0.99 |
| 2016 | 0.93 | 1.12 | 0.74 |
| 2015 | 1.24 | 2.07 | 0.87 |
| 2014 | 0.7 | 1.28 | 0.54 |
| 2013 | 0.7 | 0.91 | 0.56 |
| 2012 | 0.89 | 1.05 | 0.78 |
| 2011 | 1.32 | 1.79 | 0.94 |
| 2010 | 1.77 | 2.71 | 1.32 |
| 2009 | 2.13 | 3.53 | 0.99 |
| 2008 | 2.57 | 5.83 | 0.82 |
| 2007 | 4.96 | 7.35 | 2.83 |
| 2006 | 1.6 | 3.06 | 0.79 |
| 2005 | 1.04 | 1.53 | 0.82 |
| 2004 | 1.51 | 2.3 | 1.25 |
| 2003 | 1.77 | 2.09 | 1.6 |
| 2002 | 2.69 | 3.87 | 2.2 |
| 2001 | 3.66 | 3.94 | 3.08 |
| 2000 | 3.56 | 4.72 | 3.15 |
| 1999 | 2.54 | 3.39 | 1.43 |