| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 67.5 | 53 |
| 2015 | 67.4 | 55 |
| 2014 | 67.3 | 61 |
| 2013 | 67.2 | 65 |
| 2012 | 67 | 69 |
| 2011 | 66.8 | 75 |
| 2010 | 66.6 | 79 |
| 2009 | 66.5 | 80 |
| 2008 | 66.3 | 79 |
| 2007 | 66.1 | 78 |
| 2006 | 65.9 | 80 |
| 2005 | 65.7 | 79 |
| 2004 | 65.5 | 76 |
| 2003 | 65.4 | 73 |
| 2002 | 65.3 | 70 |
| 2001 | 65.2 | 67 |
| 2000 | 65.1 | 65 |
| 1999 | 65.1 | 64 |
| 1998 | 65 | 60 |
| 1997 | 64.9 | 59 |
| 1996 | 64.9 | 56 |
| 1995 | 64.9 | 56 |
| 1994 | 64.7 | 56 |
| 1993 | 64.5 | 61 |
| 1992 | 64.2 | 62 |
| 1991 | 63.8 | 65 |
| 1990 | 63.2 | 67 |
| 1989 | 62.6 | 68 |
| 1988 | 61.8 | 71 |
| 1987 | 60.9 | 74 |
| 1986 | 60.2 | 77 |