| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 72.9 | 9 |
| 2015 | 73.1 | 9 |
| 2014 | 73.3 | 9 |
| 2013 | 73.4 | 9 |
| 2012 | 73.3 | 11 |
| 2011 | 73.3 | 10 |
| 2010 | 73.2 | 10 |
| 2009 | 73 | 10 |
| 2008 | 72.8 | 9 |
| 2007 | 72.6 | 9 |
| 2006 | 72.4 | 9 |
| 2005 | 72.3 | 7 |
| 2004 | 72.2 | 6 |
| 2003 | 72.3 | 5 |
| 2002 | 72.4 | 4 |
| 2001 | 72.4 | 4 |
| 2000 | 72.2 | 3 |
| 1999 | 72.1 | 3 |
| 1998 | 71.8 | 4 |
| 1997 | 71.3 | 4 |
| 1996 | 71 | 4 |
| 1995 | 71 | 5 |
| 1994 | 70.7 | 5 |
| 1993 | 70.5 | 4 |
| 1992 | 70.4 | 4 |
| 1991 | 70 | 4 |
| 1990 | 69.3 | 5 |
| 1989 | 68.7 | 10 |
| 1988 | 67.9 | 17 |
| 1987 | 66.9 | 22 |
| 1986 | 66.1 | 36 |