| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 69.4 | 32 |
| 2015 | 69.6 | 30 |
| 2014 | 69.4 | 33 |
| 2013 | 69.2 | 34 |
| 2012 | 68.9 | 37 |
| 2011 | 68.6 | 45 |
| 2010 | 68.4 | 47 |
| 2009 | 68.1 | 48 |
| 2008 | 67.9 | 51 |
| 2007 | 67.6 | 54 |
| 2006 | 67.3 | 54 |
| 2005 | 67 | 58 |
| 2004 | 66.9 | 56 |
| 2003 | 66.8 | 52 |
| 2002 | 66.8 | 52 |
| 2001 | 66.9 | 51 |
| 2000 | 67 | 48 |
| 1999 | 67 | 42 |
| 1998 | 67.1 | 38 |
| 1997 | 67.2 | 35 |
| 1996 | 67.4 | 28 |
| 1995 | 67.7 | 23 |
| 1994 | 67.9 | 18 |
| 1993 | 68.3 | 16 |
| 1992 | 68.6 | 15 |
| 1991 | 69 | 9 |
| 1990 | 69.2 | 8 |
| 1989 | 69.5 | 5 |
| 1988 | 69.6 | 4 |
| 1987 | 69.7 | 4 |
| 1986 | 69.6 | 3 |