| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 20.7 | 127 |
| 2015 | 20.8 | 129 |
| 2014 | 20.8 | 129 |
| 2013 | 20.8 | 130 |
| 2012 | 20.7 | 131 |
| 2011 | 20.7 | 135 |
| 2010 | 20.7 | 135 |
| 2009 | 20.8 | 137 |
| 2008 | 20.9 | 137 |
| 2007 | 21.2 | 136 |
| 2006 | 21.5 | 136 |
| 2005 | 21.8 | 136 |
| 2004 | 22.4 | 136 |
| 2003 | 23 | 134 |
| 2002 | 23.8 | 135 |
| 2001 | 24.6 | 134 |
| 2000 | 25.6 | 136 |
| 1999 | 26.6 | 131 |
| 1998 | 27.7 | 130 |
| 1997 | 28.8 | 126 |
| 1996 | 29.8 | 123 |
| 1995 | 30.8 | 121 |
| 1994 | 31.5 | 120 |
| 1993 | 32.1 | 119 |
| 1992 | 32.5 | 120 |
| 1991 | 33 | 119 |
| 1990 | 33.6 | 118 |
| 1989 | 33.9 | 117 |
| 1988 | 34.1 | 117 |
| 1987 | 34.4 | 117 |
| 1986 | 34.5 | 119 |