| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 59.7 | 143 |
| 2015 | 59.3 | 146 |
| 2014 | 58.7 | 147 |
| 2013 | 58.1 | 148 |
| 2012 | 57.6 | 148 |
| 2011 | 57 | 149 |
| 2010 | 56.3 | 151 |
| 2009 | 55.8 | 152 |
| 2008 | 55.1 | 157 |
| 2007 | 54.5 | 160 |
| 2006 | 54 | 160 |
| 2005 | 53.6 | 164 |
| 2004 | 53.2 | 166 |
| 2003 | 53 | 167 |
| 2002 | 52.8 | 166 |
| 2001 | 52.5 | 166 |
| 2000 | 52.3 | 165 |
| 1999 | 52.1 | 165 |
| 1998 | 51.9 | 166 |
| 1997 | 51.6 | 168 |
| 1996 | 51.4 | 169 |
| 1995 | 51.3 | 169 |
| 1994 | 51.2 | 169 |
| 1993 | 51 | 170 |
| 1992 | 51 | 168 |
| 1991 | 50.9 | 165 |
| 1990 | 50.8 | 167 |
| 1989 | 50.7 | 165 |
| 1988 | 50.5 | 166 |
| 1987 | 50.4 | 164 |
| 1986 | 50.4 | 169 |