| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 68.9 | 41 |
| 2015 | 68.8 | 42 |
| 2014 | 68.7 | 43 |
| 2013 | 68.5 | 44 |
| 2012 | 68.3 | 48 |
| 2011 | 68.1 | 51 |
| 2010 | 68 | 55 |
| 2009 | 67.7 | 56 |
| 2008 | 67.3 | 60 |
| 2007 | 67 | 62 |
| 2006 | 66.6 | 67 |
| 2005 | 66.1 | 72 |
| 2004 | 65.6 | 74 |
| 2003 | 65.1 | 79 |
| 2002 | 64.6 | 79 |
| 2001 | 64 | 82 |
| 2000 | 63.6 | 82 |
| 1999 | 63 | 82 |
| 1998 | 62.5 | 82 |
| 1997 | 62 | 83 |
| 1996 | 61.6 | 83 |
| 1995 | 61.3 | 84 |
| 1994 | 60.9 | 86 |
| 1993 | 60.7 | 86 |
| 1992 | 60.4 | 86 |
| 1991 | 60.3 | 84 |
| 1990 | 60.2 | 82 |
| 1989 | 60.2 | 80 |
| 1988 | 60.3 | 79 |
| 1987 | 60.3 | 78 |
| 1986 | 60.4 | 75 |