| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 69.6 | 26 |
| 2015 | 69.5 | 31 |
| 2014 | 69.4 | 35 |
| 2013 | 69.1 | 35 |
| 2012 | 68.9 | 38 |
| 2011 | 68.6 | 44 |
| 2010 | 68.4 | 46 |
| 2009 | 68 | 52 |
| 2008 | 67.7 | 55 |
| 2007 | 67.4 | 58 |
| 2006 | 67 | 59 |
| 2005 | 66.6 | 64 |
| 2004 | 66.3 | 66 |
| 2003 | 65.9 | 65 |
| 2002 | 65.5 | 65 |
| 2001 | 65.2 | 69 |
| 2000 | 64.8 | 70 |
| 1999 | 64.4 | 71 |
| 1998 | 63.9 | 73 |
| 1997 | 63.4 | 73 |
| 1996 | 62.9 | 73 |
| 1995 | 62.5 | 74 |
| 1994 | 62 | 75 |
| 1993 | 61.6 | 75 |
| 1992 | 61.2 | 79 |
| 1991 | 60.9 | 80 |
| 1990 | 60.5 | 80 |
| 1989 | 60.2 | 81 |
| 1988 | 59.9 | 81 |
| 1987 | 59.6 | 81 |
| 1986 | 59.3 | 81 |