| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.02 | 1.25 | 0.92 |
| 2024 | 0.89 | 1.18 | 0.7 |
| 2023 | 1.23 | 1.4 | 1.06 |
| 2022 | 1.19 | 1.63 | 0.99 |
| 2021 | 1.21 | 1.52 | 1.01 |
| 2020 | 1.06 | 1.47 | 0.71 |
| 2019 | 0.87 | 1.04 | 0.77 |
| 2018 | 1.07 | 1.34 | 0.79 |
| 2017 | 1.52 | 1.96 | 1.25 |
| 2016 | 1.5 | 1.75 | 1.3 |
| 2015 | 1.85 | 2.96 | 1.36 |
| 2014 | 1.36 | 1.79 | 1.2 |
| 2013 | 1.63 | 2.25 | 1.31 |
| 2012 | 2.43 | 2.89 | 1.57 |
| 2011 | 2.74 | 3.42 | 2.12 |
| 2010 | 4.29 | 6.94 | 3.15 |
| 2009 | 3.76 | 5.31 | 2.94 |
| 2008 | 7.4 | 20.42 | 2.41 |
| 2007 | 14.25 | 18.24 | 10.54 |
| 2006 | 7.21 | 10.91 | 4.54 |
| 2005 | 4.82 | 6.1 | 3.64 |
| 2004 | 6.54 | 11.33 | 3.81 |
| 2003 | 9.31 | 11.75 | 7.53 |
| 2002 | 9.82 | 11.37 | 6.85 |
| 2001 | 10.11 | 12.88 | 6.82 |
| 2000 | 7.74 | 10.52 | 4.57 |
| 1999 | 5.8 | 7.58 | 4.58 |
| 1998 | 4.64 | 5.67 | 3.38 |
| 1997 | 4.35 | 6.17 | 2.94 |