| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.84 | 0.94 | 0.71 |
| 2024 | 0.76 | 0.9 | 0.62 |
| 2023 | 0.85 | 1.14 | 0.74 |
| 2022 | 0.94 | 1.23 | 0.78 |
| 2021 | 1.07 | 1.73 | 0.9 |
| 2020 | 1.18 | 1.48 | 0.88 |
| 2019 | 1.22 | 1.56 | 1.06 |
| 2018 | 1.29 | 1.67 | 0.86 |
| 2017 | 1.82 | 2.21 | 1.54 |
| 2016 | 1.42 | 1.72 | 1.16 |
| 2015 | 1.73 | 2.45 | 1.11 |
| 2014 | 1.48 | 1.93 | 1.13 |
| 2013 | 1.2 | 1.54 | 0.96 |
| 2012 | 1.53 | 2.13 | 1.1 |
| 2011 | 2.62 | 3.94 | 1.44 |
| 2010 | 3.29 | 4.47 | 2.01 |
| 2009 | 2.42 | 4.01 | 1.04 |
| 2008 | 1.56 | 2.7 | 0.82 |
| 2007 | 1.76 | 3.03 | 0.71 |
| 2006 | 0.66 | 0.84 | 0.44 |
| 2005 | 0.61 | 0.79 | 0.49 |
| 2004 | 1.09 | 1.54 | 0.77 |
| 2003 | 1.79 | 2.57 | 1.08 |
| 2002 | 2.39 | 3.08 | 2.08 |
| 2001 | 3.22 | 3.89 | 2.19 |
| 2000 | 5.44 | 6.26 | 3.99 |
| 1999 | 4.4 | 6.42 | 3.11 |
| 1998 | 6.29 | 8.26 | 4.44 |
| 1997 | 7.42 | 9.8 | 5.71 |