| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 69.6 | 28 |
| 2015 | 69.8 | 26 |
| 2014 | 70.1 | 28 |
| 2013 | 70.3 | 25 |
| 2012 | 70.6 | 25 |
| 2011 | 70.8 | 21 |
| 2010 | 71 | 19 |
| 2009 | 71.1 | 16 |
| 2008 | 71.2 | 14 |
| 2007 | 71.2 | 14 |
| 2006 | 71.1 | 15 |
| 2005 | 70.9 | 15 |
| 2004 | 70.5 | 15 |
| 2003 | 70 | 15 |
| 2002 | 69.4 | 15 |
| 2001 | 68.7 | 17 |
| 2000 | 67.9 | 30 |
| 1999 | 67 | 43 |
| 1998 | 66 | 52 |
| 1997 | 64.9 | 60 |
| 1996 | 64 | 70 |
| 1995 | 63.2 | 71 |
| 1994 | 62.4 | 74 |
| 1993 | 61.9 | 74 |
| 1992 | 61.5 | 75 |
| 1991 | 61.1 | 78 |
| 1990 | 60.7 | 79 |
| 1989 | 60.4 | 78 |
| 1988 | 60.2 | 80 |
| 1987 | 60 | 79 |
| 1986 | 59.9 | 78 |