| 时间 | 值 | 世界排名 |
|---|---|---|
| 2015 | 2 | 112 |
| 2014 | 3 | 98 |
| 2013 | 3.4 | 94 |
| 2012 | 4.3 | 76 |
| 2011 | 4.9 | 53 |
| 2010 | 5.4 | 60 |
| 2009 | 6.5 | 47 |
| 2008 | 6.6 | 24 |
| 2007 | 7.1 | 26 |
| 2006 | 4.7 | 52 |
| 2005 | 3.7 | 66 |
| 2004 | 4.1 | 57 |
| 2003 | 5.8 | 37 |
| 2002 | 5 | 45 |
| 2001 | 3.1 | 72 |
| 2000 | 2.7 | 79 |
| 1999 | 3 | 75 |
| 1998 | 2.2 | 90 |
| 1997 | 1.9 | 102 |
| 1996 | 3 | 62 |
| 1995 | 1.7 | 102 |
| 1994 | 1.3 | 108 |
| 1993 | 2 | 86 |
| 1992 | 2.1 | 83 |
| 1991 | 1.7 | 87 |
| 1990 | 0.5 | 113 |
| 1989 | 0.4 | 112 |
| 1988 | 0 | 123 |