| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 66.9 | 60 |
| 2015 | 67.2 | 60 |
| 2014 | 67.4 | 59 |
| 2013 | 67.6 | 59 |
| 2012 | 67.8 | 57 |
| 2011 | 67.9 | 55 |
| 2010 | 68 | 53 |
| 2009 | 68.1 | 50 |
| 2008 | 68.1 | 47 |
| 2007 | 68.1 | 44 |
| 2006 | 68 | 42 |
| 2005 | 67.9 | 40 |
| 2004 | 67.8 | 39 |
| 2003 | 67.6 | 40 |
| 2002 | 67.5 | 43 |
| 2001 | 67.3 | 44 |
| 2000 | 67.3 | 42 |
| 1999 | 67.2 | 38 |
| 1998 | 67.3 | 37 |
| 1997 | 67.3 | 32 |
| 1996 | 67.5 | 26 |
| 1995 | 67.7 | 21 |
| 1994 | 67.8 | 20 |
| 1993 | 67.9 | 18 |
| 1992 | 68.1 | 18 |
| 1991 | 68.3 | 17 |
| 1990 | 68.4 | 15 |
| 1989 | 68.4 | 13 |
| 1988 | 68.4 | 11 |
| 1987 | 68.4 | 11 |
| 1986 | 68.3 | 13 |