| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 65.9 | 81 |
| 2015 | 65.9 | 82 |
| 2014 | 65.9 | 85 |
| 2013 | 65.9 | 91 |
| 2012 | 65.8 | 92 |
| 2011 | 65.6 | 93 |
| 2010 | 65.4 | 97 |
| 2009 | 65.1 | 98 |
| 2008 | 64.7 | 101 |
| 2007 | 64.3 | 102 |
| 2006 | 63.9 | 101 |
| 2005 | 63.5 | 99 |
| 2004 | 63.1 | 99 |
| 2003 | 62.7 | 100 |
| 2002 | 62.3 | 100 |
| 2001 | 61.8 | 102 |
| 2000 | 61.2 | 101 |
| 1999 | 60.6 | 99 |
| 1998 | 60 | 103 |
| 1997 | 59.3 | 105 |
| 1996 | 58.7 | 105 |
| 1995 | 58.2 | 107 |
| 1994 | 57.7 | 106 |
| 1993 | 57.3 | 106 |
| 1992 | 57 | 106 |
| 1991 | 56.8 | 106 |
| 1990 | 56.4 | 106 |
| 1989 | 56.1 | 106 |
| 1988 | 55.8 | 106 |
| 1987 | 55.5 | 107 |
| 1986 | 55.2 | 108 |