| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.4 | 1.54 | 1.27 |
| 2024 | 1.23 | 1.86 | 0.98 |
| 2023 | 1.43 | 1.6 | 1.28 |
| 2022 | 1.54 | 1.96 | 1.31 |
| 2021 | 1.67 | 1.96 | 1.49 |
| 2020 | 2.45 | 3.23 | 1.9 |
| 2019 | 3.43 | 6.43 | 2.02 |
| 2018 | 1.88 | 3.6 | 0.98 |
| 2017 | 2.78 | 3.61 | 2.06 |
| 2016 | 6.19 | 9.58 | 3.11 |
| 2015 | 7.68 | 11.92 | 3.16 |
| 2014 | 4.77 | 5.86 | 3.87 |
| 2013 | 4.27 | 5.73 | 3.26 |
| 2012 | 20.91 | 35.32 | 3.21 |
| 2011 | 21.67 | 28.69 | 14.3 |
| 2010 | 15.82 | 19.22 | 12.7 |
| 2009 | 9.49 | 14.71 | 4.06 |
| 2008 | 5.44 | 10.46 | 2.3 |
| 2007 | 6.56 | 11.47 | 2.65 |
| 2006 | 2.72 | 3.24 | 2.03 |
| 2005 | 1.85 | 2.99 | 1.08 |
| 2004 | 2.68 | 3.61 | 2.03 |
| 2003 | 3.33 | 3.99 | 2.6 |
| 2002 | 4.11 | 5.22 | 2.2 |
| 2001 | 4.58 | 5.62 | 3.56 |
| 2000 | 3.75 | 4.96 | 2.6 |
| 1999 | 2.54 | 3.36 | 1.83 |
| 1998 | 2.27 | 3.27 | 1.42 |
| 1997 | 1.41 | 1.88 | 1.05 |