| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 64.4 | 110 |
| 2015 | 64.3 | 111 |
| 2014 | 64.2 | 112 |
| 2013 | 64 | 114 |
| 2012 | 63.6 | 118 |
| 2011 | 63.3 | 119 |
| 2010 | 62.9 | 119 |
| 2009 | 62.4 | 119 |
| 2008 | 61.8 | 121 |
| 2007 | 61 | 121 |
| 2006 | 60.3 | 123 |
| 2005 | 59.5 | 124 |
| 2004 | 58.9 | 126 |
| 2003 | 58.2 | 128 |
| 2002 | 57.4 | 128 |
| 2001 | 56.5 | 129 |
| 2000 | 55.3 | 137 |
| 1999 | 53.9 | 146 |
| 1998 | 52.6 | 160 |
| 1997 | 51.4 | 170 |
| 1996 | 50.7 | 177 |
| 1995 | 50.5 | 177 |
| 1994 | 50.4 | 176 |
| 1993 | 50.9 | 171 |
| 1992 | 51.7 | 158 |
| 1991 | 52.4 | 142 |
| 1990 | 52.8 | 136 |
| 1989 | 53.4 | 125 |
| 1988 | 53.6 | 125 |
| 1987 | 53.6 | 125 |
| 1986 | 53.8 | 123 |