| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.89 | 88 |
| 2015 | 6.7 | 89 |
| 2014 | 6.54 | 90 |
| 2013 | 6.41 | 91 |
| 2012 | 6.3 | 90 |
| 2011 | 6.2 | 90 |
| 2010 | 6.1 | 91 |
| 2009 | 5.99 | 92 |
| 2008 | 5.87 | 93 |
| 2007 | 5.76 | 93 |
| 2006 | 5.65 | 94 |
| 2005 | 5.54 | 95 |
| 2004 | 5.42 | 96 |
| 2003 | 5.31 | 96 |
| 2002 | 5.2 | 96 |
| 2001 | 5.1 | 97 |
| 2000 | 4.99 | 97 |
| 1999 | 4.9 | 97 |
| 1998 | 4.8 | 99 |
| 1997 | 4.71 | 99 |
| 1996 | 4.62 | 99 |
| 1995 | 4.53 | 98 |
| 1994 | 4.47 | 98 |
| 1993 | 4.41 | 96 |
| 1992 | 4.35 | 96 |
| 1991 | 4.29 | 96 |
| 1990 | 4.24 | 96 |
| 1989 | 4.21 | 94 |
| 1988 | 4.19 | 95 |
| 1987 | 4.17 | 91 |
| 1986 | 4.15 | 92 |