| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 67.4 | 55 |
| 2015 | 67.6 | 53 |
| 2014 | 67.8 | 53 |
| 2013 | 67.8 | 55 |
| 2012 | 67.8 | 56 |
| 2011 | 67.8 | 56 |
| 2010 | 67.8 | 57 |
| 2009 | 67.6 | 60 |
| 2008 | 67.3 | 62 |
| 2007 | 67.1 | 61 |
| 2006 | 66.9 | 63 |
| 2005 | 66.8 | 62 |
| 2004 | 66.7 | 57 |
| 2003 | 66.8 | 55 |
| 2002 | 66.9 | 50 |
| 2001 | 66.9 | 47 |
| 2000 | 67 | 47 |
| 1999 | 66.9 | 44 |
| 1998 | 66.9 | 42 |
| 1997 | 66.8 | 40 |
| 1996 | 66.7 | 39 |
| 1995 | 66.8 | 34 |
| 1994 | 66.7 | 35 |
| 1993 | 66.7 | 31 |
| 1992 | 66.6 | 29 |
| 1991 | 66.5 | 30 |
| 1990 | 66.3 | 36 |
| 1989 | 66.4 | 34 |
| 1988 | 66.4 | 33 |
| 1987 | 66.4 | 30 |
| 1986 | 66.4 | 30 |