| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 20.6 | 128 |
| 2015 | 20.8 | 128 |
| 2014 | 21.1 | 127 |
| 2013 | 21.4 | 126 |
| 2012 | 21.8 | 126 |
| 2011 | 22.1 | 129 |
| 2010 | 22.5 | 130 |
| 2009 | 22.9 | 129 |
| 2008 | 23.3 | 129 |
| 2007 | 23.7 | 130 |
| 2006 | 24.1 | 131 |
| 2005 | 24.6 | 130 |
| 2004 | 25.1 | 128 |
| 2003 | 25.6 | 128 |
| 2002 | 26.2 | 127 |
| 2001 | 26.7 | 128 |
| 2000 | 27.1 | 128 |
| 1999 | 27.6 | 128 |
| 1998 | 27.9 | 128 |
| 1997 | 28.3 | 130 |
| 1996 | 28.6 | 131 |
| 1995 | 28.9 | 131 |
| 1994 | 29.2 | 131 |
| 1993 | 29.4 | 131 |
| 1992 | 29.6 | 131 |
| 1991 | 29.8 | 132 |
| 1990 | 30 | 132 |
| 1989 | 30.2 | 131 |
| 1988 | 30.4 | 131 |
| 1987 | 30.6 | 132 |
| 1986 | 30.9 | 132 |