| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 63.9 | 119 |
| 2015 | 63.9 | 117 |
| 2014 | 63.8 | 116 |
| 2013 | 63.8 | 117 |
| 2012 | 63.8 | 115 |
| 2011 | 63.8 | 112 |
| 2010 | 63.7 | 113 |
| 2009 | 63.6 | 113 |
| 2008 | 63.5 | 111 |
| 2007 | 63.3 | 109 |
| 2006 | 63.1 | 108 |
| 2005 | 63 | 105 |
| 2004 | 62.8 | 102 |
| 2003 | 62.6 | 102 |
| 2002 | 62.5 | 98 |
| 2001 | 62.3 | 98 |
| 2000 | 62.1 | 93 |
| 1999 | 61.9 | 90 |
| 1998 | 61.8 | 90 |
| 1997 | 61.6 | 86 |
| 1996 | 61.5 | 85 |
| 1995 | 61.3 | 82 |
| 1994 | 61.1 | 82 |
| 1993 | 60.8 | 84 |
| 1992 | 60.5 | 83 |
| 1991 | 60.4 | 82 |
| 1990 | 60.3 | 81 |
| 1989 | 60.2 | 79 |
| 1988 | 60.3 | 78 |
| 1987 | 60.4 | 77 |
| 1986 | 60.5 | 74 |