| 时间 | 值 | 世界排名 |
|---|---|---|
| 2015 | 8 | 24 |
| 2014 | 6.6 | 27 |
| 2013 | 6 | 40 |
| 2012 | 5.9 | 42 |
| 2011 | 6.2 | 36 |
| 2010 | 7.8 | 28 |
| 2009 | 9.8 | 22 |
| 2008 | 7.7 | 20 |
| 2007 | 11.1 | 13 |
| 2006 | 8.9 | 18 |
| 2005 | 8.5 | 15 |
| 2004 | 11.3 | 5 |
| 2003 | 12.3 | 5 |
| 2002 | 10.4 | 6 |
| 2001 | 7.5 | 10 |
| 2000 | 6.1 | 17 |
| 1999 | 6.3 | 15 |
| 1998 | 5.7 | 21 |
| 1997 | 5.4 | 19 |
| 1996 | 5 | 25 |
| 1995 | 5.1 | 25 |
| 1994 | 6.9 | 13 |
| 1993 | 5.1 | 26 |
| 1992 | 3.4 | 43 |
| 1991 | 2.9 | 61 |
| 1990 | 2 | 75 |
| 1989 | 3.2 | 47 |
| 1988 | 4 | 29 |
| 1987 | 5.8 | 20 |
| 1986 | 5.9 | 16 |