| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 62.5 | 128 |
| 2015 | 62.8 | 125 |
| 2014 | 63.2 | 123 |
| 2013 | 63.6 | 119 |
| 2012 | 64.1 | 112 |
| 2011 | 64.5 | 109 |
| 2010 | 64.8 | 105 |
| 2009 | 65 | 100 |
| 2008 | 65.1 | 97 |
| 2007 | 65.1 | 95 |
| 2006 | 65.1 | 93 |
| 2005 | 65.1 | 87 |
| 2004 | 65.1 | 83 |
| 2003 | 65.1 | 78 |
| 2002 | 65.1 | 73 |
| 2001 | 65.2 | 70 |
| 2000 | 65.2 | 63 |
| 1999 | 65.2 | 60 |
| 1998 | 65.2 | 59 |
| 1997 | 65.3 | 56 |
| 1996 | 65.4 | 53 |
| 1995 | 65.4 | 52 |
| 1994 | 65.6 | 51 |
| 1993 | 65.7 | 49 |
| 1992 | 65.8 | 46 |
| 1991 | 66 | 43 |
| 1990 | 66.1 | 41 |
| 1989 | 66.2 | 36 |
| 1988 | 66.3 | 34 |
| 1987 | 66.3 | 34 |
| 1986 | 66.4 | 32 |