| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.9 | 12 |
| 2015 | 6 | 26 |
| 2014 | 6.7 | 24 |
| 2013 | 7.4 | 20 |
| 2012 | 7.5 | 24 |
| 2011 | 7.4 | 34 |
| 2010 | 6.5 | 56 |
| 2009 | 3.8 | 44 |
| 2008 | 7.9 | 29 |
| 2007 | 7.8 | 55 |
| 2006 | 7 | 65 |
| 2005 | 6.7 | 60 |
| 2004 | 10.3 | 20 |
| 2003 | 11 | 15 |
| 2002 | 10.8 | 6 |
| 2001 | 10.2 | 8 |
| 2000 | 8.3 | 24 |
| 1999 | 3.7 | 86 |
| 1998 | 5.3 | 50 |
| 1997 | 1.7 | 155 |
| 1996 | -16.7 | 192 |
| 1995 | -12.4 | 185 |
| 1994 | -21.3 | 180 |
| 1993 | -16.4 | 177 |
| 1992 | -29 | 175 |
| 1991 | -7.1 | 161 |
| 1990 | -.6 | 131 |
| 1989 | -6.5 | 158 |
| 1988 | 13.9 | 6 |
| 1987 | -1.2 | 143 |
| 1986 | 3.5 | 80 |