| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 60.5 | 138 |
| 2015 | 61 | 136 |
| 2014 | 61.6 | 130 |
| 2013 | 62.2 | 128 |
| 2012 | 62.9 | 121 |
| 2011 | 63.5 | 116 |
| 2010 | 64.1 | 110 |
| 2009 | 64.7 | 103 |
| 2008 | 65.2 | 96 |
| 2007 | 65.7 | 87 |
| 2006 | 66.1 | 77 |
| 2005 | 66.5 | 67 |
| 2004 | 66.9 | 54 |
| 2003 | 67.3 | 44 |
| 2002 | 67.6 | 41 |
| 2001 | 67.9 | 32 |
| 2000 | 68.2 | 22 |
| 1999 | 68.5 | 15 |
| 1998 | 68.8 | 10 |
| 1997 | 69 | 8 |
| 1996 | 69.3 | 8 |
| 1995 | 69.5 | 8 |
| 1994 | 69.6 | 6 |
| 1993 | 69.7 | 6 |
| 1992 | 69.8 | 5 |
| 1991 | 69.8 | 5 |
| 1990 | 69.7 | 4 |
| 1989 | 69.5 | 4 |
| 1988 | 69.1 | 6 |
| 1987 | 68.8 | 9 |
| 1986 | 68.4 | 10 |