| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 56.8 | 156 |
| 2015 | 56.7 | 155 |
| 2014 | 56.4 | 155 |
| 2013 | 56.2 | 154 |
| 2012 | 56.1 | 154 |
| 2011 | 55.9 | 154 |
| 2010 | 55.7 | 154 |
| 2009 | 55.5 | 155 |
| 2008 | 55.3 | 155 |
| 2007 | 55.1 | 156 |
| 2006 | 54.9 | 157 |
| 2005 | 54.8 | 156 |
| 2004 | 54.5 | 155 |
| 2003 | 54.3 | 155 |
| 2002 | 54.1 | 153 |
| 2001 | 53.9 | 151 |
| 2000 | 53.7 | 152 |
| 1999 | 53.4 | 152 |
| 1998 | 53.2 | 152 |
| 1997 | 52.9 | 150 |
| 1996 | 52.7 | 152 |
| 1995 | 52.5 | 153 |
| 1994 | 52.4 | 152 |
| 1993 | 52.3 | 151 |
| 1992 | 52.2 | 151 |
| 1991 | 52.1 | 150 |
| 1990 | 52.1 | 152 |
| 1989 | 52.1 | 148 |
| 1988 | 52 | 144 |
| 1987 | 52 | 143 |
| 1986 | 52 | 142 |