| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 1.51 | 2.11 | 1.07 |
| 2023 | 1.17 | 1.59 | 0.89 |
| 2022 | 0.85 | 1.05 | 0.69 |
| 2021 | 0.78 | 1.33 | 0.67 |
| 2020 | 0.72 | 1.31 | 0.61 |
| 2019 | 0.73 | 0.94 | 0.61 |
| 2018 | 0.79 | 1.07 | 0.57 |
| 2017 | 1.43 | 2.31 | 1.02 |
| 2016 | 1.49 | 2.11 | 1.07 |
| 2015 | 1.63 | 2.57 | 1.2 |
| 2014 | 1.3 | 1.68 | 1.07 |
| 2013 | 0.99 | 1.25 | 0.78 |
| 2012 | 1.02 | 1.3 | 0.86 |
| 2011 | 2.06 | 4.58 | 0.99 |
| 2010 | 3.32 | 4.41 | 2.58 |
| 2009 | 2.39 | 4.3 | 1.31 |
| 2008 | 2.16 | 4.23 | 0.91 |
| 2007 | 3.6 | 6.55 | 1.68 |
| 2006 | 1.5 | 1.88 | 1.21 |
| 2005 | 0.99 | 1.51 | 0.62 |
| 2004 | 1.41 | 1.78 | 1.12 |
| 2003 | 1.4 | 1.64 | 1.08 |
| 2002 | 1.58 | 2.02 | 0.96 |
| 2001 | 1.82 | 2.25 | 1.42 |
| 2000 | 1.79 | 2.24 | 1.25 |
| 1999 | 1.33 | 1.84 | 1.06 |
| 1998 | 1.55 | 2.07 | 1.12 |
| 1997 | 2.53 | 3.9 | 1.98 |