| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 2.4 | 2.85 | 2.14 |
| 2024 | 2 | 2.86 | 1.55 |
| 2023 | 2.3 | 2.79 | 1.86 |
| 2022 | 2.49 | 3.84 | 1.92 |
| 2021 | 3.13 | 4.18 | 2.49 |
| 2020 | 8.35 | 20.5 | 2.88 |
| 2019 | 10.71 | 17.37 | 8.61 |
| 2018 | 13.36 | 23.27 | 8.38 |
| 2017 | 21.12 | 26.96 | 17.98 |
| 2016 | 14.96 | 21.04 | 6.35 |
| 2015 | 9.98 | 18.78 | 5.16 |
| 2014 | 4.49 | 6.51 | 3.67 |
| 2013 | 3.95 | 4.98 | 2.91 |
| 2012 | 3.42 | 4.38 | 2.66 |
| 2011 | 4.93 | 7.44 | 3.28 |
| 2010 | 4.89 | 6.34 | 3.86 |
| 2009 | 3.67 | 5.13 | 2.31 |
| 2008 | 3.85 | 7.82 | 1.71 |
| 2007 | 6.08 | 11.06 | 2.66 |
| 2006 | 2.87 | 4.59 | 1.74 |
| 2005 | 2.61 | 3.86 | 1.59 |
| 2004 | 4.8 | 7.54 | 3.19 |
| 2003 | 5.19 | 6.48 | 2.96 |
| 2002 | 6.14 | 7.78 | 4.36 |
| 2001 | 6.18 | 7.34 | 4.62 |
| 2000 | 5.57 | 6.58 | 4.07 |
| 1999 | 4.5 | 5.82 | 3.63 |
| 1998 | 6.98 | 9.41 | 5.28 |
| 1997 | 6.96 | 10.06 | 4.85 |