| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 66 | 78 |
| 2015 | 65.7 | 86 |
| 2014 | 65.4 | 100 |
| 2013 | 65 | 102 |
| 2012 | 64.7 | 107 |
| 2011 | 64.3 | 110 |
| 2010 | 64 | 112 |
| 2009 | 63.6 | 112 |
| 2008 | 63.3 | 113 |
| 2007 | 63 | 112 |
| 2006 | 62.7 | 112 |
| 2005 | 62.4 | 110 |
| 2004 | 62.1 | 109 |
| 2003 | 61.8 | 106 |
| 2002 | 61.4 | 106 |
| 2001 | 61.1 | 104 |
| 2000 | 60.9 | 102 |
| 1999 | 60.5 | 101 |
| 1998 | 60.2 | 100 |
| 1997 | 59.8 | 100 |
| 1996 | 59.6 | 99 |
| 1995 | 59.3 | 98 |
| 1994 | 59 | 97 |
| 1993 | 58.8 | 97 |
| 1992 | 58.6 | 96 |
| 1991 | 58.4 | 96 |
| 1990 | 58.2 | 94 |
| 1989 | 58 | 93 |
| 1988 | 57.8 | 93 |
| 1987 | 57.7 | 95 |
| 1986 | 57.6 | 94 |