| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.56 | 95 |
| 2015 | 6.4 | 95 |
| 2014 | 6.27 | 95 |
| 2013 | 6.21 | 94 |
| 2012 | 6.19 | 93 |
| 2011 | 6.17 | 91 |
| 2010 | 6.14 | 90 |
| 2009 | 6.08 | 88 |
| 2008 | 6.01 | 89 |
| 2007 | 5.92 | 90 |
| 2006 | 5.83 | 90 |
| 2005 | 5.75 | 90 |
| 2004 | 5.65 | 91 |
| 2003 | 5.56 | 92 |
| 2002 | 5.47 | 91 |
| 2001 | 5.37 | 91 |
| 2000 | 5.26 | 91 |
| 1999 | 5.16 | 91 |
| 1998 | 5.05 | 90 |
| 1997 | 4.94 | 89 |
| 1996 | 4.82 | 90 |
| 1995 | 4.69 | 91 |
| 1994 | 4.55 | 95 |
| 1993 | 4.39 | 97 |
| 1992 | 4.24 | 102 |
| 1991 | 4.08 | 105 |
| 1990 | 3.92 | 111 |
| 1989 | 3.79 | 116 |
| 1988 | 3.66 | 120 |
| 1987 | 3.55 | 125 |
| 1986 | 3.45 | 127 |