| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.2 | 30 |
| 2015 | 0.1 | 169 |
| 2014 | 0.4 | 169 |
| 2013 | 2.3 | 124 |
| 2012 | 3.94 | 85 |
| 2011 | 3.91 | 99 |
| 2010 | 1.94 | 148 |
| 2009 | -.28 | 104 |
| 2008 | 4.94 | 84 |
| 2007 | 1.76 | 177 |
| 2006 | 2.5 | 168 |
| 2005 | 3 | 149 |
| 2004 | 2.34 | 165 |
| 2003 | 1.25 | 158 |
| 2002 | 5.16 | 53 |
| 2001 | 3.66 | 83 |
| 2000 | 2.5 | 146 |
| 1999 | 3.81 | 81 |
| 1998 | 3.64 | 106 |
| 1997 | 5.18 | 77 |
| 1996 | 4.46 | 89 |
| 1995 | 4.61 | 80 |
| 1994 | 3.97 | 84 |
| 1993 | 5.04 | 53 |
| 1992 | 3.27 | 76 |
| 1991 | 2.61 | 79 |
| 1990 | 4.32 | 62 |
| 1989 | 4 | 78 |
| 1988 | 6.31 | 51 |
| 1987 | 3.3 | 85 |