| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 40.9 | 35 |
| 2015 | 41.3 | 35 |
| 2014 | 41.8 | 34 |
| 2013 | 42.2 | 32 |
| 2012 | 42.6 | 30 |
| 2011 | 43 | 29 |
| 2010 | 43.2 | 29 |
| 2009 | 43.4 | 28 |
| 2008 | 43.5 | 29 |
| 2007 | 43.6 | 29 |
| 2006 | 43.7 | 29 |
| 2005 | 43.8 | 28 |
| 2004 | 44 | 28 |
| 2003 | 44.3 | 26 |
| 2002 | 44.7 | 24 |
| 2001 | 45 | 22 |
| 2000 | 45.1 | 21 |
| 1999 | 45.5 | 18 |
| 1998 | 45.8 | 19 |
| 1997 | 46 | 18 |
| 1996 | 46.3 | 16 |
| 1995 | 46.7 | 12 |
| 1994 | 47.2 | 12 |
| 1993 | 47.7 | 10 |
| 1992 | 48.2 | 7 |
| 1991 | 48.7 | 3 |
| 1990 | 49 | 3 |
| 1989 | 49.3 | 3 |
| 1988 | 49.6 | 3 |
| 1987 | 49.8 | 3 |
| 1986 | 49.9 | 2 |