| 时间 | 值 | 世界排名 |
|---|---|---|
| 2016 | 17 | 4 |
| 2015 | 15 | 6 |
| 2014 | 12.5 | 9 |
| 2013 | 12.5 | 10 |
| 2012 | 13.2 | 8 |
| 2011 | 7.9 | 22 |
| 2010 | 8.1 | 26 |
| 2009 | 4.6 | 86 |
| 2008 | 2.2 | 111 |
| 2007 | 2.5 | 115 |
| 2006 | 2.7 | 107 |
| 2005 | 2.7 | 96 |
| 2004 | 4.2 | 56 |
| 2003 | 4.5 | 56 |
| 2002 | 4.6 | 53 |
| 2001 | 3.7 | 57 |
| 2000 | 3.9 | 51 |
| 1999 | 5.3 | 32 |
| 1998 | 5.7 | 19 |
| 1997 | 6 | 11 |
| 1996 | 6.3 | 12 |
| 1995 | 6.3 | 12 |
| 1994 | 7.1 | 12 |
| 1993 | 7.6 | 7 |
| 1992 | 6.6 | 9 |
| 1991 | 6.4 | 13 |
| 1990 | 6.3 | 10 |
| 1989 | 7.4 | 10 |
| 1988 | 7.9 | 6 |
| 1987 | 10.1 | 5 |
| 1986 | 9.4 | 7 |