| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 57.1 | 154 |
| 2015 | 57 | 153 |
| 2014 | 56.8 | 152 |
| 2013 | 56.6 | 152 |
| 2012 | 56.4 | 152 |
| 2011 | 56.2 | 152 |
| 2010 | 56 | 152 |
| 2009 | 55.8 | 153 |
| 2008 | 55.5 | 153 |
| 2007 | 55.2 | 155 |
| 2006 | 55 | 156 |
| 2005 | 54.7 | 157 |
| 2004 | 54.4 | 159 |
| 2003 | 54 | 158 |
| 2002 | 53.6 | 156 |
| 2001 | 53.3 | 159 |
| 2000 | 53 | 161 |
| 1999 | 52.6 | 162 |
| 1998 | 52.3 | 162 |
| 1997 | 51.9 | 164 |
| 1996 | 51.7 | 165 |
| 1995 | 51.4 | 168 |
| 1994 | 51.2 | 168 |
| 1993 | 51 | 169 |
| 1992 | 50.9 | 169 |
| 1991 | 50.9 | 166 |
| 1990 | 50.9 | 165 |
| 1989 | 50.9 | 162 |
| 1988 | 50.9 | 158 |
| 1987 | 51 | 154 |
| 1986 | 51.1 | 155 |