| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 55.8 | 160 |
| 2015 | 55.5 | 161 |
| 2014 | 55.2 | 162 |
| 2013 | 54.8 | 163 |
| 2012 | 54.4 | 164 |
| 2011 | 54 | 165 |
| 2010 | 53.6 | 168 |
| 2009 | 53.3 | 170 |
| 2008 | 53 | 174 |
| 2007 | 52.8 | 174 |
| 2006 | 52.6 | 173 |
| 2005 | 52.4 | 174 |
| 2004 | 52.2 | 174 |
| 2003 | 52 | 173 |
| 2002 | 51.9 | 174 |
| 2001 | 51.9 | 173 |
| 2000 | 51.9 | 174 |
| 1999 | 51.8 | 170 |
| 1998 | 51.8 | 168 |
| 1997 | 51.8 | 166 |
| 1996 | 51.8 | 164 |
| 1995 | 51.8 | 164 |
| 1994 | 51.7 | 164 |
| 1993 | 51.6 | 159 |
| 1992 | 51.5 | 160 |
| 1991 | 51.4 | 161 |
| 1990 | 51.4 | 159 |
| 1989 | 51.2 | 156 |
| 1988 | 51.1 | 155 |
| 1987 | 51 | 155 |
| 1986 | 50.9 | 157 |