| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 65 | 102 |
| 2015 | 65.5 | 95 |
| 2014 | 66 | 84 |
| 2013 | 66.4 | 79 |
| 2012 | 66.8 | 74 |
| 2011 | 67.1 | 70 |
| 2010 | 67.3 | 66 |
| 2009 | 67.3 | 66 |
| 2008 | 67.2 | 63 |
| 2007 | 67 | 64 |
| 2006 | 66.5 | 69 |
| 2005 | 66 | 75 |
| 2004 | 65.2 | 82 |
| 2003 | 64.4 | 86 |
| 2002 | 63.5 | 92 |
| 2001 | 62.5 | 94 |
| 2000 | 61.4 | 100 |
| 1999 | 60.4 | 103 |
| 1998 | 59.4 | 108 |
| 1997 | 58.4 | 109 |
| 1996 | 57.5 | 111 |
| 1995 | 56.7 | 114 |
| 1994 | 55.8 | 117 |
| 1993 | 55.1 | 120 |
| 1992 | 54.4 | 125 |
| 1991 | 53.8 | 125 |
| 1990 | 53.3 | 127 |
| 1989 | 52.8 | 135 |
| 1988 | 52.3 | 139 |
| 1987 | 51.9 | 147 |
| 1986 | 51.5 | 149 |