| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 14.7 | 176 |
| 2015 | 14.8 | 174 |
| 2014 | 14.9 | 170 |
| 2013 | 15.1 | 169 |
| 2012 | 15.3 | 167 |
| 2011 | 15.5 | 168 |
| 2010 | 15.4 | 168 |
| 2009 | 15.5 | 169 |
| 2008 | 15.5 | 173 |
| 2007 | 15.4 | 178 |
| 2006 | 15.4 | 180 |
| 2005 | 15.7 | 178 |
| 2004 | 15.9 | 179 |
| 2003 | 16.3 | 179 |
| 2002 | 16.8 | 179 |
| 2001 | 17.1 | 179 |
| 2000 | 17.3 | 180 |
| 1999 | 17.5 | 181 |
| 1998 | 17.7 | 179 |
| 1997 | 17.9 | 179 |
| 1996 | 18.1 | 180 |
| 1995 | 18.4 | 178 |
| 1994 | 18.7 | 179 |
| 1993 | 19 | 180 |
| 1992 | 19.3 | 178 |
| 1991 | 19.5 | 178 |
| 1990 | 19.8 | 179 |
| 1989 | 20.1 | 177 |
| 1988 | 20.3 | 177 |
| 1987 | 20.6 | 178 |
| 1986 | 20.7 | 179 |