| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.47 | 1.52 | 1.41 |
| 2024 | 1.31 | 1.5 | 1.2 |
| 2023 | 1.3 | 1.44 | 1.12 |
| 2022 | 1.15 | 1.24 | 1.05 |
| 2021 | 1.04 | 1.21 | 0.83 |
| 2020 | 0.95 | 1.26 | 0.84 |
| 2019 | 1.22 | 1.42 | 1.09 |
| 2018 | 1.24 | 1.37 | 1.09 |
| 2017 | 1.33 | 1.79 | 1.14 |
| 2016 | 1.02 | 1.66 | 0.76 |
| 2015 | 0.76 | 0.89 | 0.62 |
| 2014 | 0.62 | 0.78 | 0.55 |
| 2013 | 0.63 | 0.75 | 0.56 |
| 2012 | 0.6 | 0.66 | 0.52 |
| 2011 | 0.77 | 1.01 | 0.54 |
| 2010 | 1.11 | 1.25 | 0.98 |
| 2009 | 1.11 | 1.36 | 0.91 |
| 2008 | 1.44 | 2.73 | 0.79 |
| 2007 | 2.27 | 3.59 | 1.27 |
| 2006 | 1.13 | 1.26 | 1 |
| 2005 | 0.45 | 1.06 | 0.26 |
| 2004 | 0.32 | 0.46 | 0.26 |
| 2003 | 0.36 | 0.39 | 0.32 |
| 2002 | 0.39 | 0.43 | 0.31 |
| 2001 | 0.4 | 0.61 | 0.2 |
| 2000 | 0.25 | 0.31 | 0.2 |
| 1999 | 0.18 | 0.29 | 0.13 |
| 1998 | 0.27 | 0.44 | 0.13 |
| 1997 | 0.58 | 0.82 | 0.31 |