| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.98 | 1.05 | 0.86 |
| 2024 | 0.94 | 1.36 | 0.67 |
| 2023 | 1.09 | 1.43 | 0.89 |
| 2022 | 1.01 | 1.71 | 0.78 |
| 2021 | 0.93 | 1.3 | 0.69 |
| 2020 | 0.95 | 1.11 | 0.78 |
| 2019 | 1.1 | 1.37 | 0.84 |
| 2018 | 0.96 | 1.19 | 0.79 |
| 2017 | 1.61 | 2.03 | 1.1 |
| 2016 | 2.79 | 4.42 | 1.86 |
| 2015 | 3.47 | 6.28 | 2.39 |
| 2014 | 2.86 | 4.04 | 2.27 |
| 2013 | 3.73 | 5.77 | 2.92 |
| 2012 | 4.81 | 8.1 | 3.65 |
| 2011 | 0 | ||
| 2010 | 0 | ||
| 2009 | 0 | ||
| 2008 | 0 | ||
| 2007 | 0 | -0.56 | |
| 2006 | 3.5 | 3.86 | 2.94 |
| 2005 | 2.52 | 4.62 | 1.05 |
| 2004 | 3.13 | 4.76 | 1.94 |
| 2003 | 4.2 | 5.36 | 3.15 |
| 2002 | 7.43 | 9.13 | 6.41 |
| 2001 | 11.42 | 14.05 | 7.91 |
| 2000 | 11.3 | 16 | 6.45 |
| 1999 | 9.32 | 12.63 | 6.37 |
| 1998 | 9.26 | 12.48 | 7.16 |