| 时间 | 值 | 世界排名 |
|---|---|---|
| 2015 | 12 | 13 |
| 2014 | 12.3 | 10 |
| 2013 | 13.2 | 8 |
| 2012 | 14.3 | 6 |
| 2011 | 14.5 | 9 |
| 2010 | 16.4 | 7 |
| 2009 | 17 | 8 |
| 2008 | 13.9 | 7 |
| 2007 | 12.8 | 12 |
| 2006 | 9.4 | 16 |
| 2005 | 6.4 | 26 |
| 2004 | 5.5 | 33 |
| 2003 | 5.4 | 41 |
| 2002 | 4.5 | 56 |
| 2001 | 5.9 | 17 |
| 2000 | 5.8 | 20 |
| 1999 | 6.4 | 14 |
| 1998 | 5.9 | 16 |
| 1997 | 6.9 | 8 |
| 1996 | 7.9 | 7 |
| 1995 | 6.7 | 9 |
| 1994 | 6.1 | 15 |
| 1993 | 4.2 | 39 |
| 1992 | 3.7 | 38 |
| 1991 | 3.7 | 43 |
| 1990 | 4.5 | 24 |
| 1989 | 5.2 | 17 |
| 1988 | 5 | 17 |
| 1987 | 5.3 | 24 |
| 1986 | 5.3 | 24 |