| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.14 | 1.29 | 1 |
| 2024 | 1.01 | 1.26 | 0.78 |
| 2023 | 1.7 | 2.87 | 1.16 |
| 2022 | 1.95 | 2.42 | 1.58 |
| 2021 | 2.39 | 2.9 | 2.05 |
| 2020 | 2.39 | 3.26 | 1.85 |
| 2019 | 2.05 | 2.48 | 1.48 |
| 2018 | 2.17 | 3.47 | 1.32 |
| 2017 | 3.81 | 5.2 | 2.83 |
| 2016 | 4.1 | 4.86 | 2.99 |
| 2015 | 4.56 | 7.83 | 2.77 |
| 2014 | 4.18 | 7.39 | 2.95 |
| 2013 | 4.63 | 6.24 | 4.08 |
| 2012 | 3.88 | 4.69 | 3.13 |
| 2011 | 5.3 | 6.45 | 3.41 |
| 2010 | 5.44 | 7.33 | 3.99 |
| 2009 | 4.58 | 6.65 | 2.22 |
| 2008 | 3.06 | 5.01 | 1.73 |
| 2007 | 3.67 | 5.74 | 1.2 |
| 2006 | 1.19 | 1.41 | 0.92 |
| 2005 | 1.42 | 1.95 | 1.15 |
| 2004 | 1.97 | 2.65 | 1.41 |
| 2003 | 3.13 | 3.97 | 1.99 |
| 2002 | 4.44 | 4.97 | 3.22 |
| 2001 | 5.78 | 8.04 | 3.76 |
| 2000 | 11.92 | 14.5 | 6 |
| 1999 | 5.27 | 6.77 | 3.77 |
| 1998 | 7.36 | 8.82 | 5.52 |
| 1997 | 7.09 | 9.8 | 4.6 |