| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.38 | 0.41 | 0.34 |
| 2024 | 0.45 | 0.49 | 0.4 |
| 2023 | 0.55 | 0.66 | 0.44 |
| 2022 | 0.41 | 0.48 | 0.33 |
| 2021 | 0.39 | 0.44 | 0.37 |
| 2020 | 0.39 | 0.45 | 0.36 |
| 2019 | 0.48 | 0.53 | 0.44 |
| 2018 | 0.55 | 0.61 | 0.49 |
| 2017 | 0.68 | 0.8 | 0.6 |
| 2016 | 0.75 | 0.98 | 0.66 |
| 2015 | 1.09 | 1.46 | 0.85 |
| 2014 | 0.85 | 1.05 | 0.76 |
| 2013 | 1.15 | 1.97 | 0.83 |
| 2012 | 0.81 | 1.57 | 0.67 |
| 2011 | 0.78 | 1.02 | 0.61 |
| 2010 | 1.09 | 1.19 | 0.98 |
| 2009 | 0.98 | 1.29 | 0.72 |
| 2008 | 1 | 2.1 | 0.63 |
| 2007 | 2.08 | 2.89 | 1.51 |
| 2006 | 1.26 | 1.55 | 1.05 |
| 2005 | 0.45 | 1.12 | 0.25 |
| 2004 | 0.5 | 0.81 | 0.29 |
| 2003 | 0.58 | 0.79 | 0.46 |
| 2002 | 0.68 | 1.03 | 0.45 |
| 2001 | 1.61 | 2.34 | 0.91 |
| 2000 | 0.73 | 0.97 | 0.4 |
| 1999 | 0.6 | 1.09 | 0.35 |
| 1998 | 0.49 | 0.68 | 0.26 |
| 1997 | 0.85 | 1.2 | 0.55 |