| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 66.1 | 75 |
| 2015 | 66.2 | 76 |
| 2014 | 66.6 | 71 |
| 2013 | 67 | 68 |
| 2012 | 67.3 | 65 |
| 2011 | 67.8 | 58 |
| 2010 | 68.2 | 49 |
| 2009 | 68.4 | 45 |
| 2008 | 68.6 | 44 |
| 2007 | 68.7 | 36 |
| 2006 | 68.9 | 33 |
| 2005 | 69 | 28 |
| 2004 | 69 | 24 |
| 2003 | 68.9 | 22 |
| 2002 | 68.8 | 19 |
| 2001 | 68.7 | 18 |
| 2000 | 68.5 | 15 |
| 1999 | 68.5 | 14 |
| 1998 | 68.5 | 12 |
| 1997 | 68.4 | 13 |
| 1996 | 68.3 | 13 |
| 1995 | 68.2 | 15 |
| 1994 | 68 | 17 |
| 1993 | 67.7 | 20 |
| 1992 | 67.3 | 24 |
| 1991 | 66.9 | 25 |
| 1990 | 66.6 | 32 |
| 1989 | 66.2 | 35 |
| 1988 | 65.9 | 41 |
| 1987 | 65.5 | 44 |
| 1986 | 65.2 | 45 |