| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.02 | 100 |
| 2015 | 5.87 | 98 |
| 2014 | 5.73 | 99 |
| 2013 | 5.64 | 100 |
| 2012 | 5.57 | 100 |
| 2011 | 5.52 | 99 |
| 2010 | 5.47 | 99 |
| 2009 | 5.36 | 100 |
| 2008 | 5.26 | 99 |
| 2007 | 5.16 | 101 |
| 2006 | 5.05 | 101 |
| 2005 | 4.94 | 101 |
| 2004 | 4.83 | 104 |
| 2003 | 4.71 | 105 |
| 2002 | 4.59 | 106 |
| 2001 | 4.46 | 109 |
| 2000 | 4.34 | 110 |
| 1999 | 4.18 | 111 |
| 1998 | 4.04 | 115 |
| 1997 | 3.89 | 117 |
| 1996 | 3.77 | 122 |
| 1995 | 3.65 | 124 |
| 1994 | 3.58 | 127 |
| 1993 | 3.51 | 132 |
| 1992 | 3.46 | 134 |
| 1991 | 3.41 | 134 |
| 1990 | 3.38 | 132 |
| 1989 | 3.36 | 132 |
| 1988 | 3.36 | 132 |
| 1987 | 3.37 | 131 |
| 1986 | 3.38 | 131 |