| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | -.58 | 158 |
| 2015 | -.97 | 175 |
| 2014 | -1.2 | 177 |
| 2013 | -.78 | 164 |
| 2012 | 0.6 | 95 |
| 2011 | 2.72 | 15 |
| 2010 | 5.53 | 1 |
| 2009 | 8.51 | 1 |
| 2008 | 11.03 | 1 |
| 2007 | 12.08 | 1 |
| 2006 | 11.31 | 1 |
| 2005 | 9.18 | 1 |
| 2004 | 6.67 | 2 |
| 2003 | 4.32 | 5 |
| 2002 | 3.15 | 12 |
| 2001 | 3.14 | 11 |
| 2000 | 3.3 | 12 |
| 1999 | 3.03 | 14 |
| 1998 | 2.88 | 18 |
| 1997 | 2.8 | 19 |
| 1996 | 4.06 | 4 |
| 1995 | 5.72 | 2 |
| 1994 | 6.03 | 5 |
| 1993 | 6.31 | 4 |
| 1992 | 6.44 | 3 |
| 1991 | 6.43 | 2 |
| 1990 | 6.46 | 2 |
| 1989 | 6.56 | 2 |
| 1988 | 6.61 | 3 |
| 1987 | 6.53 | 3 |
| 1986 | 6.56 | 1 |