| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 66.2 | 73 |
| 2015 | 66.9 | 65 |
| 2014 | 67.6 | 57 |
| 2013 | 68.3 | 48 |
| 2012 | 69 | 35 |
| 2011 | 69.7 | 31 |
| 2010 | 70.3 | 26 |
| 2009 | 70.7 | 19 |
| 2008 | 71 | 17 |
| 2007 | 71.1 | 15 |
| 2006 | 71.2 | 14 |
| 2005 | 71.2 | 12 |
| 2004 | 71 | 11 |
| 2003 | 70.8 | 9 |
| 2002 | 70.5 | 8 |
| 2001 | 70.2 | 8 |
| 2000 | 69.8 | 8 |
| 1999 | 69.4 | 8 |
| 1998 | 69.1 | 9 |
| 1997 | 68.8 | 10 |
| 1996 | 68.5 | 12 |
| 1995 | 68.1 | 16 |
| 1994 | 67.6 | 22 |
| 1993 | 67 | 25 |
| 1992 | 66.4 | 35 |
| 1991 | 66 | 42 |
| 1990 | 65.8 | 47 |
| 1989 | 65.4 | 49 |
| 1988 | 65.2 | 48 |
| 1987 | 65.2 | 47 |
| 1986 | 65.1 | 46 |