| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 2.37 | 2.54 | 2.19 |
| 2024 | 2.42 | 2.73 | 1.94 |
| 2023 | 3.5 | 4.26 | 2.51 |
| 2022 | 3 | 3.29 | 2.52 |
| 2021 | 3.98 | 5.26 | 2.66 |
| 2020 | 3.95 | 4.71 | 3 |
| 2019 | 3.31 | 4.03 | 2.34 |
| 2018 | 2.9 | 3.56 | 2.38 |
| 2017 | 2.59 | 3.56 | 2.17 |
| 2016 | 2.41 | 2.77 | 2.01 |
| 2015 | 2.39 | 3.24 | 1.86 |
| 2014 | 1.91 | 2.37 | 1.4 |
| 2013 | 2.27 | 3.76 | 1.6 |
| 2012 | 3.82 | 5.35 | 2.39 |
| 2011 | 9.22 | 13.3 | 4.06 |
| 2010 | 7.77 | 11.85 | 5.07 |
| 2009 | 2.47 | 5.68 | 0.83 |
| 2008 | 1.58 | 3.19 | 0.6 |
| 2007 | 2.3 | 3.97 | 1.3 |
| 2006 | 0.89 | 1.34 | 0.53 |
| 2005 | 0.2 | 0.59 | 0.08 |
| 2004 | 0.2 | 0.28 | 0.14 |
| 2003 | 0.24 | 0.28 | 0.23 |
| 2002 | 0.36 | 0.44 | 0.32 |
| 2001 | 0.51 | 0.82 | 0.27 |
| 2000 | 0.22 | 0.29 | 0.18 |
| 1999 | 0.21 | 0.37 | 0.15 |
| 1998 | 0.36 | 0.61 | 0.17 |
| 1997 | 0.72 | 0.98 | 0.48 |