| 时间 | 值 | 世界排名 |
|---|---|---|
| 2013 | 0 | 153 |
| 2012 | 0 | 152 |
| 2011 | 0.1 | 135 |
| 2010 | 0.2 | 127 |
| 2009 | 0.1 | 130 |
| 2008 | 0.1 | 129 |
| 2007 | 0.1 | 130 |
| 2006 | 0.1 | 130 |
| 2005 | 0.1 | 133 |
| 2004 | 0.1 | 139 |
| 2003 | 0.1 | 140 |
| 2002 | 0.1 | 138 |
| 2001 | 7.4 | 102 |
| 2000 | 12.5 | 99 |
| 1999 | 13.9 | 94 |
| 1998 | 13.8 | 94 |
| 1997 | 15.5 | 97 |
| 1996 | 16.7 | 88 |
| 1995 | 15.5 | 92 |
| 1994 | 14.7 | 92 |
| 1993 | 14.4 | 90 |
| 1992 | 15.4 | 88 |
| 1991 | 16.3 | 80 |
| 1990 | 17.9 | 76 |
| 1989 | 18.2 | 77 |
| 1988 | 16.1 | 78 |
| 1987 | 16.5 | 76 |
| 1986 | 16.6 | 75 |