| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 65.6 | 87 |
| 2015 | 65.8 | 84 |
| 2014 | 65.9 | 87 |
| 2013 | 65.9 | 92 |
| 2012 | 65.9 | 89 |
| 2011 | 65.9 | 89 |
| 2010 | 65.9 | 89 |
| 2009 | 66 | 87 |
| 2008 | 66.2 | 81 |
| 2007 | 66.3 | 77 |
| 2006 | 66.5 | 70 |
| 2005 | 66.7 | 63 |
| 2004 | 66.9 | 53 |
| 2003 | 67.1 | 46 |
| 2002 | 67.4 | 45 |
| 2001 | 67.6 | 40 |
| 2000 | 67.8 | 33 |
| 1999 | 68 | 25 |
| 1998 | 68 | 21 |
| 1997 | 68.1 | 19 |
| 1996 | 68.2 | 17 |
| 1995 | 68.3 | 13 |
| 1994 | 68.4 | 13 |
| 1993 | 68.5 | 13 |
| 1992 | 68.7 | 13 |
| 1991 | 68.9 | 10 |
| 1990 | 69.1 | 9 |
| 1989 | 69.3 | 6 |
| 1988 | 69.5 | 5 |
| 1987 | 69.7 | 3 |
| 1986 | 69.7 | 2 |