| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.96 | 1.06 | 0.91 |
| 2024 | 0.84 | 1.42 | 0.68 |
| 2023 | 0.9 | 1.07 | 0.81 |
| 2022 | 0.94 | 1.15 | 0.79 |
| 2021 | 1.02 | 1.42 | 0.83 |
| 2020 | 0.93 | 1.08 | 0.84 |
| 2019 | 1.12 | 1.57 | 0.97 |
| 2018 | 1.63 | 2.53 | 0.98 |
| 2017 | 2.15 | 2.52 | 1.75 |
| 2016 | 2.17 | 3.18 | 1.76 |
| 2015 | 3.7 | 5.43 | 2.71 |
| 2014 | 2.38 | 3.48 | 1.52 |
| 2013 | 1.5 | 2.03 | 1.06 |
| 2012 | 1.61 | 2.05 | 1.11 |
| 2011 | 1.97 | 2.4 | 1.54 |
| 2010 | 1.88 | 2.68 | 1.33 |
| 2009 | 1.9 | 2.56 | 0.93 |
| 2008 | 2.23 | 5.37 | 0.84 |
| 2007 | 4.6 | 6.3 | 2.49 |
| 2006 | 2.05 | 2.79 | 1.5 |
| 2005 | 1.98 | 2.43 | 1.44 |
| 2004 | 2.91 | 3.79 | 1.29 |
| 2003 | 2.72 | 3.13 | 2.36 |
| 2002 | 3.51 | 3.93 | 2.52 |
| 2001 | 4.68 | 5.63 | 3.27 |
| 2000 | 8.7 | 11.73 | 7.39 |
| 1999 | 7.34 | 11.08 | 3.6 |
| 1998 | 5.69 | 7.7 | 3.52 |