| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.38 | 1.63 | 1.21 |
| 2024 | 1.25 | 1.52 | 1 |
| 2023 | 1.4 | 1.64 | 1.23 |
| 2022 | 1.89 | 2.51 | 1.45 |
| 2021 | 2.12 | 4.2 | 1.64 |
| 2020 | 1.96 | 2.75 | 1.71 |
| 2019 | 2.26 | 3.5 | 1.74 |
| 2018 | 3.4 | 5.52 | 2.06 |
| 2017 | 6.41 | 7.84 | 4.86 |
| 2016 | 7.11 | 9 | 5.87 |
| 2015 | 6.48 | 10.07 | 3.56 |
| 2014 | 3.26 | 4.44 | 2.42 |
| 2013 | 3 | 3.84 | 2.4 |
| 2012 | 3.86 | 5.07 | 2.85 |
| 2011 | 5.58 | 8.43 | 3.41 |
| 2010 | 3.69 | 4.53 | 2.76 |
| 2009 | 2.85 | 4.43 | 1.29 |
| 2008 | 2.36 | 4.51 | 1.08 |
| 2007 | 3.15 | 5.22 | 1.83 |
| 2006 | 2.03 | 2.48 | 1.77 |
| 2005 | 1.61 | 2.43 | 0.79 |
| 2004 | 2.21 | 2.98 | 1.82 |
| 2003 | 2.77 | 3.49 | 1.87 |
| 2002 | 3.59 | 4.18 | 2.71 |
| 2001 | 3.93 | 5.48 | 3.05 |
| 2000 | 2.86 | 3.89 | 1.98 |
| 1999 | 2.43 | 3.01 | 2.02 |
| 1998 | 3.1 | 4.48 | 2.4 |
| 1997 | 2.24 | 2.99 | 1.7 |