| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.8 | 0.86 | 0.74 |
| 2024 | 0.98 | 1.28 | 0.76 |
| 2023 | 1.13 | 2.01 | 0.91 |
| 2022 | 0.89 | 1.09 | 0.77 |
| 2021 | 1.15 | 1.42 | 0.96 |
| 2020 | 1.54 | 1.82 | 1.29 |
| 2019 | 1.62 | 2 | 1.43 |
| 2018 | 2.21 | 3.03 | 1.59 |
| 2017 | 3.88 | 5.4 | 2.65 |
| 2016 | 4.35 | 4.73 | 3.84 |
| 2015 | 4.82 | 6.81 | 3.78 |
| 2014 | 4.76 | 8.17 | 2.97 |
| 2013 | 5.37 | 6.35 | 4.09 |
| 2012 | 5.28 | 6.53 | 3.92 |
| 2011 | 7.2 | 9.43 | 4.81 |
| 2010 | 10.2 | 12.28 | 7.94 |
| 2009 | 8.75 | 10.69 | 7.59 |
| 2008 | 9.17 | 14.7 | 5.1 |
| 2007 | 9.02 | 13.53 | 4.65 |
| 2006 | 3.91 | 5.33 | 2.96 |
| 2005 | 2.78 | 3.24 | 2.33 |
| 2004 | 4.1 | 6.07 | 3.13 |
| 2003 | 5.31 | 6.95 | 3.61 |
| 2002 | 9.3 | 15.14 | 5.36 |
| 2001 | 19.73 | 26.8 | 12.49 |
| 2000 | 15.73 | 23.61 | 6.36 |
| 1999 | 5.75 | 7.42 | 4.3 |
| 1998 | 3.82 | 4.94 | 2.53 |
| 1997 | 3.6 | 5.33 | 2.25 |