| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 64.9 | 103 |
| 2015 | 64.4 | 109 |
| 2014 | 63.7 | 117 |
| 2013 | 63 | 122 |
| 2012 | 62.2 | 127 |
| 2011 | 61.4 | 128 |
| 2010 | 60.6 | 129 |
| 2009 | 59.7 | 131 |
| 2008 | 58.9 | 134 |
| 2007 | 58 | 137 |
| 2006 | 57.1 | 141 |
| 2005 | 56.2 | 142 |
| 2004 | 55.2 | 149 |
| 2003 | 54.3 | 156 |
| 2002 | 53.4 | 162 |
| 2001 | 52.6 | 165 |
| 2000 | 51.9 | 173 |
| 1999 | 51.3 | 176 |
| 1998 | 50.9 | 176 |
| 1997 | 50.6 | 180 |
| 1996 | 50.3 | 181 |
| 1995 | 50.1 | 181 |
| 1994 | 49.8 | 181 |
| 1993 | 49.7 | 182 |
| 1992 | 49.7 | 181 |
| 1991 | 49.6 | 180 |
| 1990 | 49.7 | 181 |
| 1989 | 49.8 | 178 |
| 1988 | 50 | 178 |
| 1987 | 50.1 | 176 |
| 1986 | 50.2 | 173 |