| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 2.5 | 2.66 | 2.41 |
| 2024 | 2.36 | 2.84 | 2.08 |
| 2023 | 2.47 | 2.81 | 2.11 |
| 2022 | 2.71 | 3.7 | 2.35 |
| 2021 | 3.68 | 5.39 | 2.79 |
| 2020 | 3.24 | 4.41 | 2.54 |
| 2019 | 4.05 | 5.23 | 2.69 |
| 2018 | 5.16 | 6.55 | 3.72 |
| 2017 | 5.62 | 6.43 | 4.91 |
| 2016 | 4.88 | 5.64 | 4.38 |
| 2015 | 6.24 | 7.86 | 4.97 |
| 2014 | 6.18 | 8.53 | 5.1 |
| 2013 | 8.65 | 10.65 | 6.88 |
| 2012 | 6.74 | 7.57 | 5.88 |
| 2011 | 8.76 | 10.1 | 7.07 |
| 2010 | 9.93 | 13.05 | 8.51 |
| 2009 | 8.47 | 13.1 | 5.54 |
| 2008 | 10.7 | 16.13 | 7.92 |
| 2007 | 14.31 | 18.01 | 11.38 |
| 2006 | 10.02 | 13.75 | 7.51 |
| 2005 | 7.32 | 8.54 | 5.83 |
| 2004 | 5.83 | 6.95 | 4.92 |
| 2003 | 6.31 | 7.49 | 5.33 |
| 2002 | 9.14 | 11.14 | 7.15 |
| 2001 | 10.43 | 12.96 | 8.42 |
| 2000 | 8.03 | 9.65 | 5.51 |
| 1999 | 7.19 | 10.13 | 4.47 |
| 1998 | 7.33 | 9.55 | 5.87 |
| 1997 | 4.69 | 6.32 | 3.74 |