| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 59.6 | 146 |
| 2015 | 59.3 | 145 |
| 2014 | 59.1 | 145 |
| 2013 | 58.8 | 145 |
| 2012 | 58.3 | 146 |
| 2011 | 58 | 146 |
| 2010 | 57.9 | 146 |
| 2009 | 57.8 | 144 |
| 2008 | 57.8 | 142 |
| 2007 | 57.8 | 139 |
| 2006 | 57.5 | 138 |
| 2005 | 57 | 139 |
| 2004 | 56.7 | 139 |
| 2003 | 56.4 | 139 |
| 2002 | 56 | 139 |
| 2001 | 55.6 | 139 |
| 2000 | 55.2 | 141 |
| 1999 | 54.9 | 140 |
| 1998 | 54.6 | 136 |
| 1997 | 54.3 | 137 |
| 1996 | 54 | 136 |
| 1995 | 53.8 | 137 |
| 1994 | 53.5 | 134 |
| 1993 | 53.3 | 132 |
| 1992 | 53.1 | 132 |
| 1991 | 52.8 | 135 |
| 1990 | 52.6 | 140 |
| 1989 | 52.6 | 136 |
| 1988 | 52.7 | 135 |
| 1987 | 52.6 | 137 |
| 1986 | 52.5 | 139 |