| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.82 | 0.86 | 0.79 |
| 2024 | 0.84 | 0.98 | 0.7 |
| 2023 | 0.85 | 0.96 | 0.74 |
| 2022 | 1 | 1.63 | 0.78 |
| 2021 | 0.98 | 1.42 | 0.83 |
| 2020 | 0.94 | 1.11 | 0.86 |
| 2019 | 1.03 | 1.14 | 0.9 |
| 2018 | 1.06 | 1.26 | 0.88 |
| 2017 | 1.48 | 2.2 | 1.18 |
| 2016 | 1.58 | 2.16 | 1.38 |
| 2015 | 2.17 | 3.68 | 1.47 |
| 2014 | 1.1 | 1.83 | 0.96 |
| 2013 | 1.29 | 1.7 | 0.99 |
| 2012 | 1.61 | 2.2 | 1.37 |
| 2011 | 1.59 | 1.95 | 1.3 |
| 2010 | 1.62 | 2.1 | 1.25 |
| 2009 | 1.61 | 1.94 | 1.23 |
| 2008 | 1.81 | 3.28 | 1.06 |
| 2007 | 2.99 | 3.99 | 1.48 |
| 2006 | 1.17 | 1.5 | 1.05 |
| 2005 | 1.36 | 1.73 | 1.05 |
| 2004 | 2.25 | 3.67 | 1.54 |
| 2003 | 3.16 | 3.74 | 2.47 |
| 2002 | 5 | 6.17 | 4.38 |
| 2001 | 6.38 | 7.77 | 5.41 |
| 2000 | 7.88 | 10.44 | 5.32 |
| 1999 | 7.18 | 10.7 | 5.42 |
| 1998 | 8.56 | 12.4 | 6.16 |