| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.66 | 93 |
| 2015 | 6.48 | 93 |
| 2014 | 6.32 | 94 |
| 2013 | 6.2 | 95 |
| 2012 | 6.1 | 95 |
| 2011 | 6 | 95 |
| 2010 | 5.9 | 94 |
| 2009 | 5.79 | 96 |
| 2008 | 5.68 | 96 |
| 2007 | 5.57 | 96 |
| 2006 | 5.47 | 97 |
| 2005 | 5.38 | 98 |
| 2004 | 5.3 | 98 |
| 2003 | 5.23 | 98 |
| 2002 | 5.17 | 98 |
| 2001 | 5.11 | 96 |
| 2000 | 5.04 | 96 |
| 1999 | 4.97 | 94 |
| 1998 | 4.89 | 93 |
| 1997 | 4.81 | 94 |
| 1996 | 4.73 | 94 |
| 1995 | 4.64 | 96 |
| 1994 | 4.57 | 94 |
| 1993 | 4.49 | 94 |
| 1992 | 4.42 | 94 |
| 1991 | 4.34 | 94 |
| 1990 | 4.27 | 95 |
| 1989 | 4.19 | 96 |
| 1988 | 4.11 | 99 |
| 1987 | 4.04 | 101 |
| 1986 | 3.98 | 103 |