| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 64 | 118 |
| 2015 | 64.1 | 114 |
| 2014 | 64.4 | 109 |
| 2013 | 64.7 | 105 |
| 2012 | 64.9 | 104 |
| 2011 | 65.2 | 101 |
| 2010 | 65.4 | 96 |
| 2009 | 65.5 | 95 |
| 2008 | 65.7 | 92 |
| 2007 | 65.8 | 84 |
| 2006 | 66 | 79 |
| 2005 | 66.1 | 73 |
| 2004 | 66.2 | 67 |
| 2003 | 66.3 | 60 |
| 2002 | 66.4 | 57 |
| 2001 | 66.6 | 53 |
| 2000 | 66.7 | 52 |
| 1999 | 66.8 | 47 |
| 1998 | 66.9 | 41 |
| 1997 | 67.1 | 38 |
| 1996 | 67.2 | 31 |
| 1995 | 67.4 | 26 |
| 1994 | 67.4 | 24 |
| 1993 | 67.4 | 22 |
| 1992 | 67.4 | 22 |
| 1991 | 67.4 | 22 |
| 1990 | 67.4 | 22 |
| 1989 | 67.2 | 24 |
| 1988 | 67.1 | 22 |
| 1987 | 67 | 21 |
| 1986 | 66.8 | 26 |