| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0 | ||
| 2024 | 0 | ||
| 2023 | 0 | ||
| 2022 | 0 | ||
| 2021 | 1.38 | 1.64 | 1.21 |
| 2020 | 1.26 | 2.06 | 0.83 |
| 2019 | 1.07 | 1.25 | 0.91 |
| 2018 | 1.25 | 1.56 | 1.02 |
| 2017 | 1.71 | 2.08 | 1.46 |
| 2016 | 1.78 | 2.11 | 1.55 |
| 2015 | 2.15 | 3.2 | 1.53 |
| 2014 | 1.51 | 1.86 | 1.35 |
| 2013 | 1.64 | 2.08 | 1.34 |
| 2012 | 2.42 | 3.26 | 1.65 |
| 2011 | 4.94 | 8.57 | 2.78 |
| 2010 | 4.73 | 6.19 | 3.33 |
| 2009 | 3.04 | 4.3 | 1.57 |
| 2008 | 4.52 | 8.1 | 1 |
| 2007 | 3.9 | 6.98 | 1.72 |
| 2006 | 1.57 | 1.99 | 1.07 |
| 2005 | 1.11 | 1.31 | 0.98 |
| 2004 | 1.46 | 1.87 | 1.14 |
| 2003 | 1.74 | 2.18 | 1.41 |
| 2002 | 2.53 | 2.83 | 1.93 |
| 2001 | 4.42 | 5.34 | 3.61 |
| 2000 | 4.17 | 5.43 | 2.88 |
| 1999 | 2.94 | 4 | 2.3 |
| 1998 | 3.66 | 4.8 | 2.97 |
| 1997 | 3.76 | 5.52 | 2.66 |