| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 67.3 | 56 |
| 2015 | 67.6 | 54 |
| 2014 | 67.9 | 50 |
| 2013 | 68.1 | 53 |
| 2012 | 68.2 | 50 |
| 2011 | 68.4 | 48 |
| 2010 | 68.5 | 43 |
| 2009 | 68.7 | 43 |
| 2008 | 68.8 | 38 |
| 2007 | 68.9 | 33 |
| 2006 | 68.9 | 31 |
| 2005 | 68.9 | 29 |
| 2004 | 68.7 | 30 |
| 2003 | 68.4 | 31 |
| 2002 | 68.1 | 32 |
| 2001 | 67.9 | 36 |
| 2000 | 67.9 | 32 |
| 1999 | 67.6 | 30 |
| 1998 | 67.6 | 29 |
| 1997 | 67.6 | 26 |
| 1996 | 67.5 | 25 |
| 1995 | 67.1 | 31 |
| 1994 | 66.9 | 31 |
| 1993 | 66.5 | 36 |
| 1992 | 66.1 | 42 |
| 1991 | 65.8 | 46 |
| 1990 | 65.8 | 43 |
| 1989 | 65.7 | 44 |
| 1988 | 65.7 | 43 |
| 1987 | 65.7 | 42 |
| 1986 | 65.7 | 39 |