| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.27 | 1.39 | 1.13 |
| 2024 | 1.17 | 1.49 | 0.85 |
| 2023 | 1.2 | 1.39 | 1.06 |
| 2022 | 1.06 | 1.65 | 0.82 |
| 2021 | 0.88 | 1.06 | 0.74 |
| 2020 | 0.84 | 1.15 | 0.72 |
| 2019 | 0.92 | 1.16 | 0.8 |
| 2018 | 1.04 | 1.4 | 0.78 |
| 2017 | 1.96 | 2.57 | 1.34 |
| 2016 | 2.27 | 2.98 | 1.62 |
| 2015 | 2.33 | 3.74 | 1.53 |
| 2014 | 1.76 | 2.19 | 1.46 |
| 2013 | 2.51 | 5.81 | 1.63 |
| 2012 | 2.75 | 3.38 | 2.31 |
| 2011 | 4.37 | 5.45 | 2.53 |
| 2010 | 5.85 | 8.58 | 4.69 |
| 2009 | 4.1 | 5.7 | 2.35 |
| 2008 | 4.08 | 8.96 | 1.78 |
| 2007 | 5.88 | 8.89 | 2.13 |
| 2006 | 1.89 | 2.63 | 1.06 |
| 2005 | 1.37 | 2.13 | 0.97 |
| 2004 | 2.26 | 2.97 | 1.56 |
| 2003 | 2.36 | 2.96 | 1.81 |
| 2002 | 3.29 | 4.05 | 2.57 |
| 2001 | 5.1 | 6.36 | 3.7 |
| 2000 | 4.8 | 5.82 | 3.57 |
| 1999 | 4.34 | 5.74 | 3.47 |
| 1998 | 4.58 | 6.6 | 2.92 |
| 1997 | 4.31 | 6.71 | 2.85 |