| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 6.8 | 9.93 | 5.74 |
| 2024 | 5.91 | 7.9 | 4.74 |
| 2023 | 6.39 | 10.09 | 4.31 |
| 2022 | 2.19 | 5.52 | 1.18 |
| 2021 | 1.13 | 1.74 | 0.81 |
| 2020 | 1.03 | 1.42 | 0.81 |
| 2019 | 1.12 | 1.49 | 0.95 |
| 2018 | 1.49 | 2.16 | 0.95 |
| 2017 | 2.19 | 2.84 | 1.74 |
| 2016 | 2.44 | 3.54 | 2.13 |
| 2015 | 3.57 | 6.82 | 2.22 |
| 2014 | 1.99 | 2.79 | 1.59 |
| 2013 | 2.48 | 3.52 | 1.89 |
| 2012 | 1.93 | 3.44 | 1.49 |
| 2011 | 2.53 | 3.34 | 1.63 |
| 2010 | 2.58 | 3.41 | 1.85 |
| 2009 | 2.56 | 3.87 | 1.39 |
| 2008 | 2.27 | 4.86 | 0.9 |
| 2007 | 3.47 | 5.63 | 1.34 |
| 2006 | 1.25 | 1.57 | 0.9 |
| 2005 | 0.97 | 1.24 | 0.81 |
| 2004 | 1.49 | 2.07 | 1.04 |
| 2003 | 2 | 2.44 | 1.61 |
| 2002 | 2.97 | 3.3 | 2.37 |
| 2001 | 3.5 | 4.14 | 2.6 |
| 2000 | 2.64 | 3.09 | 2.06 |
| 1999 | 2.27 | 2.7 | 1.89 |
| 1998 | 2.8 | 3.49 | 2.16 |
| 1997 | 4.04 | 5.71 | 2.97 |