| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 68.9 | 39 |
| 2015 | 69.7 | 29 |
| 2014 | 70.3 | 25 |
| 2013 | 70.8 | 20 |
| 2012 | 71.4 | 18 |
| 2011 | 71.8 | 14 |
| 2010 | 72 | 12 |
| 2009 | 72.1 | 12 |
| 2008 | 71.9 | 12 |
| 2007 | 71.6 | 12 |
| 2006 | 71.3 | 12 |
| 2005 | 71 | 13 |
| 2004 | 70.6 | 14 |
| 2003 | 70.2 | 14 |
| 2002 | 69.9 | 12 |
| 2001 | 69.6 | 11 |
| 2000 | 69.3 | 11 |
| 1999 | 68.7 | 12 |
| 1998 | 68.1 | 19 |
| 1997 | 67.5 | 27 |
| 1996 | 67 | 35 |
| 1995 | 66.5 | 41 |
| 1994 | 66.3 | 42 |
| 1993 | 66.3 | 42 |
| 1992 | 66.3 | 37 |
| 1991 | 66.5 | 33 |
| 1990 | 66.8 | 26 |
| 1989 | 66.9 | 25 |
| 1988 | 67.1 | 23 |
| 1987 | 67.2 | 20 |
| 1986 | 67.4 | 20 |