| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 16.2 | 162 |
| 2015 | 16.1 | 163 |
| 2014 | 15.9 | 163 |
| 2013 | 15.7 | 165 |
| 2012 | 15.5 | 165 |
| 2011 | 15.3 | 169 |
| 2010 | 15.1 | 173 |
| 2009 | 15 | 176 |
| 2008 | 14.9 | 179 |
| 2007 | 14.9 | 182 |
| 2006 | 15 | 183 |
| 2005 | 15.2 | 183 |
| 2004 | 15.5 | 183 |
| 2003 | 16 | 182 |
| 2002 | 16.5 | 180 |
| 2001 | 17 | 180 |
| 2000 | 17.6 | 177 |
| 1999 | 18.2 | 177 |
| 1998 | 18.7 | 173 |
| 1997 | 19.3 | 171 |
| 1996 | 19.9 | 169 |
| 1995 | 20.6 | 168 |
| 1994 | 21 | 168 |
| 1993 | 21.4 | 167 |
| 1992 | 21.8 | 165 |
| 1991 | 22.1 | 164 |
| 1990 | 22.2 | 164 |
| 1989 | 22.3 | 163 |
| 1988 | 22.3 | 165 |
| 1987 | 22.2 | 167 |
| 1986 | 22.2 | 168 |