| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 16.6 | 158 |
| 2015 | 16.7 | 158 |
| 2014 | 16.8 | 157 |
| 2013 | 16.9 | 156 |
| 2012 | 17 | 156 |
| 2011 | 17.1 | 157 |
| 2010 | 17.3 | 159 |
| 2009 | 17.5 | 159 |
| 2008 | 17.7 | 158 |
| 2007 | 18 | 158 |
| 2006 | 18.3 | 159 |
| 2005 | 18.6 | 157 |
| 2004 | 19 | 158 |
| 2003 | 19.4 | 159 |
| 2002 | 19.8 | 158 |
| 2001 | 20.2 | 158 |
| 2000 | 20.5 | 159 |
| 1999 | 20.7 | 159 |
| 1998 | 21 | 161 |
| 1997 | 21.2 | 161 |
| 1996 | 21.6 | 160 |
| 1995 | 22.1 | 158 |
| 1994 | 22.4 | 157 |
| 1993 | 22.8 | 156 |
| 1992 | 23.2 | 155 |
| 1991 | 23.5 | 156 |
| 1990 | 23.8 | 156 |