| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.92 | 1.6 | 0.53 |
| 2024 | 0.5 | 0.75 | 0.29 |
| 2023 | 0.64 | 0.75 | 0.51 |
| 2022 | 0.7 | 0.98 | 0.57 |
| 2021 | 0.69 | 0.8 | 0.55 |
| 2020 | 0.82 | 0.95 | 0.74 |
| 2019 | 0.97 | 1.29 | 0.77 |
| 2018 | 1.54 | 2.14 | 1.05 |
| 2017 | 2.01 | 2.37 | 1.65 |
| 2016 | 2.34 | 3.67 | 1.8 |
| 2015 | 2.57 | 3.79 | 1.67 |
| 2014 | 1.82 | 2.37 | 1.53 |
| 2013 | 2.05 | 2.28 | 1.7 |
| 2012 | 1.61 | 1.85 | 1.3 |
| 2011 | 1.76 | 2.42 | 1.33 |
| 2010 | 2.01 | 2.86 | 1.42 |
| 2009 | 2.33 | 3.57 | 0.86 |
| 2008 | 1.7 | 3.54 | 0.71 |
| 2007 | 3.34 | 5.38 | 1.99 |
| 2006 | 1.5 | 2.61 | 1.17 |
| 2005 | 1.03 | 1.3 | 0.84 |
| 2004 | 1.29 | 2 | 0.87 |
| 2003 | 1.85 | 2.35 | 1.34 |
| 2002 | 2.71 | 3.09 | 2.07 |
| 2001 | 3.51 | 4.44 | 2.52 |
| 2000 | 3.89 | 4.84 | 3.3 |
| 1999 | 3.56 | 4.73 | 2.59 |
| 1998 | 4.8 | 7.27 | 3.48 |
| 1997 | 6.12 | 12.33 | 3.82 |