| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 61.7 | 131 |
| 2015 | 62.2 | 128 |
| 2014 | 62.9 | 126 |
| 2013 | 63.6 | 118 |
| 2012 | 64.4 | 109 |
| 2011 | 65.1 | 103 |
| 2010 | 65.7 | 93 |
| 2009 | 66.2 | 85 |
| 2008 | 66.5 | 77 |
| 2007 | 66.7 | 70 |
| 2006 | 66.9 | 62 |
| 2005 | 67 | 56 |
| 2004 | 67 | 51 |
| 2003 | 66.9 | 50 |
| 2002 | 66.7 | 53 |
| 2001 | 66.2 | 56 |
| 2000 | 65.5 | 60 |
| 1999 | 65.3 | 59 |
| 1998 | 64.9 | 61 |
| 1997 | 64.6 | 65 |
| 1996 | 64.5 | 62 |
| 1995 | 65 | 55 |
| 1994 | 65.1 | 55 |
| 1993 | 65.4 | 52 |
| 1992 | 65.7 | 48 |
| 1991 | 65.6 | 49 |
| 1990 | 65 | 55 |
| 1989 | 64 | 61 |
| 1988 | 62.8 | 64 |
| 1987 | 61.7 | 68 |
| 1986 | 61.1 | 70 |