| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.911 | 9 |
| 2015 | 8.212 | 13 |
| 2014 | 7.813 | 16 |
| 2013 | 8.298 | 21 |
| 2012 | 8.011 | 28 |
| 2011 | 9.482 | 12 |
| 2010 | 9.667 | 20 |
| 2009 | 9.588 | 13 |
| 2008 | 10.478 | 20 |
| 2007 | 16.07 | 10 |
| 2006 | 14.133 | 8 |
| 2005 | 12.359 | 10 |
| 2004 | 10.124 | 24 |
| 2003 | 9.539 | 17 |
| 2002 | 10.482 | 12 |
| 2001 | 10.265 | 12 |
| 2000 | 9.768 | 14 |
| 1999 | 9.258 | 13 |
| 1998 | 8.394 | 16 |
| 1997 | 10.439 | 15 |
| 1996 | 9.208 | 14 |
| 1995 | 10.083 | 12 |
| 1994 | 11.37 | 11 |
| 1993 | 12.168 | 8 |
| 1992 | 12.614 | 4 |
| 1991 | 9.181 | 10 |
| 1990 | 2.669 | 68 |
| 1989 | 5.861 | 32 |
| 1988 | 13.163 | 6 |
| 1987 | 14.665 | 7 |
| 1986 | 12.308 | 5 |