| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 66 | 79 |
| 2015 | 66.3 | 75 |
| 2014 | 66.5 | 72 |
| 2013 | 66.6 | 72 |
| 2012 | 66.7 | 76 |
| 2011 | 66.8 | 76 |
| 2010 | 67 | 72 |
| 2009 | 67.1 | 71 |
| 2008 | 67.1 | 65 |
| 2007 | 67.2 | 60 |
| 2006 | 67.1 | 56 |
| 2005 | 67 | 57 |
| 2004 | 67 | 52 |
| 2003 | 66.9 | 51 |
| 2002 | 66.8 | 51 |
| 2001 | 66.9 | 50 |
| 2000 | 67.1 | 45 |
| 1999 | 67.2 | 39 |
| 1998 | 67.4 | 33 |
| 1997 | 67.6 | 25 |
| 1996 | 67.8 | 22 |
| 1995 | 67.9 | 20 |
| 1994 | 68 | 16 |
| 1993 | 68.2 | 17 |
| 1992 | 68.3 | 16 |
| 1991 | 68.5 | 16 |
| 1990 | 68.6 | 12 |
| 1989 | 68.6 | 11 |
| 1988 | 68.6 | 10 |
| 1987 | 68.6 | 10 |
| 1986 | 68.6 | 9 |