| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.95 | 22 |
| 2015 | 3.52 | 18 |
| 2014 | 5.4 | 7 |
| 2013 | 4.88 | 7 |
| 2012 | 3.59 | 16 |
| 2011 | 3.5 | 17 |
| 2010 | 4.24 | 10 |
| 2009 | 4.39 | 13 |
| 2008 | 3.76 | 13 |
| 2007 | 3.36 | 18 |
| 2006 | 4.71 | 6 |
| 2005 | 4.83 | 7 |
| 2004 | 4.16 | 16 |
| 2003 | 4.72 | 12 |
| 2002 | 3.51 | 26 |
| 2001 | 4.52 | 15 |
| 2000 | 6.39 | 7 |
| 1999 | 17.33 | 2 |
| 1998 | 2.64 | 46 |
| 1997 | 5.97 | 10 |
| 1996 | 2.45 | 47 |
| 1995 | 4.71 | 16 |
| 1994 | 5.71 | 15 |
| 1993 | 17.55 | 3 |
| 1992 | 7.68 | 10 |
| 1991 | 7.1 | 11 |
| 1990 | 17.46 | 3 |
| 1989 | 19.43 | 1 |
| 1988 | 21.98 | 1 |
| 1987 | 22.25 | 1 |
| 1986 | 17.3 | 2 |