| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 61.9 | 130 |
| 2015 | 61.6 | 132 |
| 2014 | 61.2 | 135 |
| 2013 | 60.8 | 135 |
| 2012 | 60.3 | 135 |
| 2011 | 59.8 | 135 |
| 2010 | 59.3 | 139 |
| 2009 | 58.9 | 138 |
| 2008 | 58.4 | 138 |
| 2007 | 58 | 136 |
| 2006 | 57.6 | 137 |
| 2005 | 57.2 | 137 |
| 2004 | 56.9 | 137 |
| 2003 | 56.6 | 136 |
| 2002 | 56.3 | 136 |
| 2001 | 56.1 | 134 |
| 2000 | 56 | 130 |
| 1999 | 55.2 | 132 |
| 1998 | 54.5 | 141 |
| 1997 | 53.9 | 142 |
| 1996 | 53.4 | 146 |
| 1995 | 52.9 | 146 |
| 1994 | 52.6 | 149 |
| 1993 | 52.4 | 148 |
| 1992 | 52.4 | 146 |
| 1991 | 52.4 | 143 |
| 1990 | 52.3 | 146 |
| 1989 | 52.1 | 146 |
| 1988 | 51.8 | 151 |
| 1987 | 51.4 | 153 |
| 1986 | 51 | 156 |