| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.35 | 1.49 | 1.23 |
| 2024 | 1.15 | 1.88 | 0.91 |
| 2023 | 1.11 | 1.24 | 1.03 |
| 2022 | 1.15 | 1.34 | 1.01 |
| 2021 | 1.31 | 1.51 | 1.2 |
| 2020 | 1.65 | 2.05 | 1.46 |
| 2019 | 2.28 | 3.45 | 1.69 |
| 2018 | 1.73 | 2.66 | 1.29 |
| 2017 | 2.39 | 3.35 | 1.83 |
| 2016 | 2.87 | 4.35 | 2.55 |
| 2015 | 4.61 | 8.48 | 2.73 |
| 2014 | 2.29 | 3.6 | 1.89 |
| 2013 | 2.03 | 2.61 | 1.61 |
| 2012 | 1.97 | 2.48 | 1.6 |
| 2011 | 2.78 | 3.91 | 1.84 |
| 2010 | 4.54 | 6.65 | 3.28 |
| 2009 | 6.74 | 8.62 | 3.59 |
| 2008 | 7 | 14.97 | 2.25 |
| 2007 | 7.22 | 11.86 | 1.85 |
| 2006 | 1.68 | 2.16 | 1.09 |
| 2005 | 1.24 | 1.6 | 0.97 |
| 2004 | 2.12 | 3.49 | 1.59 |
| 2003 | 3.47 | 5.74 | 2.78 |
| 2002 | 5.37 | 6.67 | 3 |
| 2001 | 5.16 | 6.26 | 4.08 |
| 2000 | 7.14 | 12.4 | 3.9 |
| 1999 | 4.42 | 5.96 | 3.43 |
| 1998 | 6.79 | 8.52 | 5.53 |
| 1997 | 7.47 | 12.82 | 3.61 |