| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.75 | 0.79 | 0.71 |
| 2024 | 0.7 | 0.87 | 0.61 |
| 2023 | 0.69 | 0.76 | 0.64 |
| 2022 | 0.74 | 0.9 | 0.62 |
| 2021 | 0.88 | 1.01 | 0.79 |
| 2020 | 0.91 | 1.01 | 0.84 |
| 2019 | 0.96 | 1.13 | 0.83 |
| 2018 | 1.03 | 1.34 | 0.76 |
| 2017 | 1.39 | 1.56 | 1.26 |
| 2016 | 1.53 | 2.03 | 1.38 |
| 2015 | 2.5 | 3.9 | 1.59 |
| 2014 | 1.49 | 2.87 | 1.16 |
| 2013 | 1.43 | 1.88 | 1.12 |
| 2012 | 1.45 | 1.79 | 1.05 |
| 2011 | 2.03 | 2.57 | 1.44 |
| 2010 | 3.24 | 5.25 | 2.13 |
| 2009 | 3.89 | 5.36 | 2.41 |
| 2008 | 9.88 | 28.92 | 1.57 |
| 2007 | 9.06 | 20.84 | 2.78 |
| 2006 | 2.4 | 3.24 | 1.52 |
| 2005 | 2.12 | 2.97 | 1.4 |
| 2004 | 3.82 | 5.87 | 2.74 |
| 2003 | 7.17 | 12.54 | 3.98 |
| 2002 | 6.25 | 7.38 | 4.9 |
| 2001 | 7.6 | 8.91 | 5.92 |
| 2000 | 7.67 | 9.16 | 4.28 |
| 1999 | 3.75 | 6.02 | 2.33 |
| 1998 | 3.72 | 5.49 | 2.49 |