| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 65 | 101 |
| 2015 | 65.5 | 94 |
| 2014 | 65.7 | 90 |
| 2013 | 66.1 | 84 |
| 2012 | 66.5 | 81 |
| 2011 | 66.6 | 80 |
| 2010 | 66.3 | 84 |
| 2009 | 66 | 89 |
| 2008 | 65.2 | 95 |
| 2007 | 64.3 | 101 |
| 2006 | 63.5 | 105 |
| 2005 | 62.8 | 106 |
| 2004 | 62 | 111 |
| 2003 | 61.4 | 110 |
| 2002 | 60.8 | 109 |
| 2001 | 60.2 | 110 |
| 2000 | 59.5 | 113 |
| 1999 | 58.7 | 114 |
| 1998 | 58 | 114 |
| 1997 | 57.4 | 115 |
| 1996 | 56.8 | 115 |
| 1995 | 56.4 | 115 |
| 1994 | 56.1 | 115 |
| 1993 | 55.8 | 114 |
| 1992 | 55.6 | 115 |
| 1991 | 55.6 | 116 |
| 1990 | 55.6 | 114 |
| 1989 | 55.6 | 111 |
| 1988 | 55.6 | 108 |
| 1987 | 55.7 | 106 |
| 1986 | 55.7 | 105 |