| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 40 | 40 |
| 2015 | 40.1 | 40 |
| 2014 | 40.3 | 41 |
| 2013 | 40.5 | 41 |
| 2012 | 40.7 | 41 |
| 2011 | 40.9 | 42 |
| 2010 | 41 | 42 |
| 2009 | 41.3 | 42 |
| 2008 | 41.5 | 41 |
| 2007 | 41.8 | 38 |
| 2006 | 42 | 36 |
| 2005 | 42.3 | 35 |
| 2004 | 42.6 | 36 |
| 2003 | 43 | 35 |
| 2002 | 43.3 | 36 |
| 2001 | 43.7 | 35 |
| 2000 | 44 | 33 |
| 1999 | 44.3 | 32 |
| 1998 | 44.7 | 30 |
| 1997 | 45 | 30 |
| 1996 | 45.2 | 28 |
| 1995 | 45.5 | 26 |
| 1994 | 45.7 | 26 |
| 1993 | 45.8 | 28 |
| 1992 | 45.9 | 28 |
| 1991 | 46 | 28 |
| 1990 | 45.9 | 28 |
| 1989 | 45.9 | 33 |
| 1988 | 45.9 | 35 |
| 1987 | 45.8 | 37 |
| 1986 | 45.7 | 37 |