| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.71 | 0.94 | 0.64 |
| 2024 | 0.62 | 0.76 | 0.51 |
| 2023 | 0.79 | 0.91 | 0.7 |
| 2022 | 1.01 | 1.67 | 0.74 |
| 2021 | 0.98 | 1.38 | 0.78 |
| 2020 | 1.36 | 1.52 | 1.16 |
| 2019 | 1.41 | 1.81 | 1.19 |
| 2018 | 1.68 | 2.24 | 1.24 |
| 2017 | 2.46 | 2.91 | 2.09 |
| 2016 | 2.38 | 2.71 | 1.84 |
| 2015 | 2.62 | 4.2 | 1.57 |
| 2014 | 2.15 | 2.62 | 1.84 |
| 2013 | 2.14 | 2.7 | 1.77 |
| 2012 | 2.35 | 3.29 | 1.77 |
| 2011 | 3.26 | 4.49 | 1.85 |
| 2010 | 2.67 | 4.18 | 1.85 |
| 2009 | 2.11 | 2.74 | 1.37 |
| 2008 | 2.02 | 3.62 | 0.95 |
| 2007 | 2.75 | 4.3 | 0.9 |
| 2006 | 1 | 1.37 | 0.81 |
| 2005 | 1.02 | 1.44 | 0.72 |
| 2004 | 2.1 | 3.37 | 1.44 |
| 2003 | 2.49 | 4.04 | 2.06 |
| 2002 | 4.56 | 5.31 | 3.05 |
| 2001 | 5.59 | 6.79 | 3.97 |
| 2000 | 5.53 | 7.12 | 4.08 |
| 1999 | 4.25 | 5.27 | 3.47 |
| 1998 | 4.62 | 6.64 | 3.56 |
| 1997 | 4.77 | 7.63 | 2.83 |