| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 14.8 | 175 |
| 2015 | 14.9 | 172 |
| 2014 | 14.9 | 172 |
| 2013 | 14.9 | 173 |
| 2012 | 14.8 | 176 |
| 2011 | 14.7 | 179 |
| 2010 | 14.6 | 182 |
| 2009 | 14.6 | 182 |
| 2008 | 14.5 | 184 |
| 2007 | 14.4 | 186 |
| 2006 | 14.4 | 187 |
| 2005 | 14.3 | 190 |
| 2004 | 14.3 | 190 |
| 2003 | 14.3 | 191 |
| 2002 | 14.4 | 192 |
| 2001 | 14.5 | 193 |
| 2000 | 14.8 | 193 |
| 1999 | 15 | 193 |
| 1998 | 15.3 | 192 |
| 1997 | 15.7 | 192 |
| 1996 | 16.2 | 191 |
| 1995 | 16.7 | 191 |
| 1994 | 17.3 | 189 |
| 1993 | 17.9 | 186 |
| 1992 | 18.6 | 183 |
| 1991 | 19.3 | 179 |
| 1990 | 20 | 177 |
| 1989 | 20.7 | 175 |
| 1988 | 21.4 | 172 |
| 1987 | 22 | 168 |
| 1986 | 22.7 | 167 |