| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0 | ||
| 2024 | 0 | ||
| 2023 | 0.87 | 1.25 | 0.56 |
| 2022 | 0.84 | 1.09 | 0.58 |
| 2021 | 0.69 | 1.38 | 0.55 |
| 2020 | 1.13 | 1.43 | 0.82 |
| 2019 | 0.96 | 1.05 | 0.85 |
| 2018 | 0.94 | 1.33 | 0.71 |
| 2017 | 1.33 | 1.57 | 1.13 |
| 2016 | 1.7 | 2.59 | 1.5 |
| 2015 | 2.3 | 4.25 | 1.31 |
| 2014 | 0.99 | 1.5 | 0.8 |
| 2013 | 0.94 | 1.12 | 0.82 |
| 2012 | 1.06 | 1.3 | 0.91 |
| 2011 | 1.45 | 1.83 | 1.07 |
| 2010 | 1.97 | 2.72 | 1.57 |
| 2009 | 1.97 | 2.92 | 1.01 |
| 2008 | 3.62 | 11.03 | 0.84 |
| 2007 | 8.22 | 12.34 | 3.81 |
| 2006 | 2.51 | 4.35 | 1.39 |
| 2005 | 1.88 | 2.36 | 1.58 |
| 2004 | 2.61 | 3.56 | 2 |
| 2003 | 3.44 | 4.32 | 2.51 |
| 2002 | 4.56 | 5.35 | 2.94 |
| 2001 | 5.97 | 7.61 | 4.49 |
| 2000 | 5.29 | 6.87 | 3.64 |
| 1999 | 4.88 | 6.54 | 3.46 |
| 1998 | 5.42 | 6.7 | 4.42 |
| 1997 | 5.53 | 8.21 | 3.52 |