| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 65.4 | 92 |
| 2015 | 65.1 | 101 |
| 2014 | 64.7 | 105 |
| 2013 | 64.3 | 110 |
| 2012 | 63.9 | 114 |
| 2011 | 63.4 | 117 |
| 2010 | 62.8 | 120 |
| 2009 | 62.3 | 121 |
| 2008 | 61.6 | 122 |
| 2007 | 60.9 | 123 |
| 2006 | 60.2 | 125 |
| 2005 | 59.6 | 123 |
| 2004 | 59.4 | 121 |
| 2003 | 59.5 | 120 |
| 2002 | 59.6 | 118 |
| 2001 | 59.8 | 115 |
| 2000 | 59.8 | 111 |
| 1999 | 60.1 | 105 |
| 1998 | 60.2 | 99 |
| 1997 | 60.2 | 97 |
| 1996 | 60.1 | 96 |
| 1995 | 60 | 95 |
| 1994 | 60 | 92 |
| 1993 | 60.1 | 90 |
| 1992 | 60.2 | 87 |
| 1991 | 60.1 | 85 |
| 1990 | 59.9 | 84 |
| 1989 | 59.6 | 83 |
| 1988 | 59 | 86 |
| 1987 | 58.1 | 90 |
| 1986 | 57.3 | 95 |