| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 1.04 | 1.26 | 0.93 |
| 2025 | 0.99 | 1.11 | 0.85 |
| 2024 | 0.95 | 1.34 | 0.69 |
| 2023 | 1.1 | 1.23 | 1 |
| 2022 | 1.15 | 1.53 | 0.9 |
| 2021 | 1.13 | 1.48 | 0.93 |
| 2020 | 1.25 | 1.67 | 0.98 |
| 2019 | 1.19 | 1.77 | 0.87 |
| 2018 | 1.02 | 1.49 | 0.69 |
| 2017 | 1.72 | 2.31 | 1.4 |
| 2016 | 2.04 | 2.56 | 1.62 |
| 2015 | 2.55 | 3.8 | 1.53 |
| 2014 | 1.94 | 3.3 | 1.41 |
| 2013 | 1.65 | 2.09 | 1.31 |
| 2012 | 1.77 | 2.39 | 1.1 |
| 2011 | 2.55 | 3.86 | 1.1 |
| 2010 | 3.86 | 5.23 | 2.93 |
| 2009 | 4.29 | 5.87 | 2.02 |
| 2008 | 3.36 | 6.59 | 1.2 |
| 2007 | 4.45 | 6.04 | 2.68 |
| 2006 | 1.99 | 2.71 | 1.26 |
| 2005 | 1.9 | 2.5 | 1.48 |
| 2004 | 4.16 | 9.72 | 2.47 |
| 2003 | 7.75 | 9.05 | 6.98 |
| 2002 | 8.39 | 9.49 | 5.9 |
| 2001 | 9.91 | 11.77 | 7.17 |
| 2000 | 9.06 | 12.29 | 6.79 |
| 1999 | 5.6 | 7.3 | 4.03 |
| 1998 | 3.89 | 5.15 | 3.2 |
| 1997 | 5.81 | 9.16 | 4.48 |