| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.858 | 18 |
| 2015 | 6.908 | 36 |
| 2014 | 6.917 | 39 |
| 2013 | 7.683 | 31 |
| 2012 | 7.642 | 43 |
| 2011 | 6.742 | 45 |
| 2010 | 6.233 | 51 |
| 2009 | 6.492 | 60 |
| 2008 | 6.583 | 63 |
| 2007 | 6.1 | 66 |
| 2006 | 6.017 | 60 |
| 2005 | 7.225 | 47 |
| 2004 | 7.725 | 40 |
| 2003 | 8.225 | 44 |
| 2002 | 9.333 | 36 |
| 2001 | 9.458 | 43 |
| 2000 | 9.457 | 49 |
| 1999 | 9.218 | 55 |
| 1998 | 9.363 | 60 |
| 1997 | 9.835 | 62 |
| 1996 | 10.542 | 62 |
| 1995 | 10.917 | 59 |
| 1994 | 11.833 | 40 |
| 1993 | 12 | 43 |
| 1992 | 12 | 44 |
| 1991 | 12 | 45 |
| 1990 | 12 | 42 |
| 1989 | 11.667 | 41 |
| 1988 | 11 | 38 |
| 1987 | 11 | 33 |
| 1986 | 11 | 33 |