| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.02 | 28 |
| 2015 | 3.96 | 33 |
| 2014 | 3.91 | 33 |
| 2013 | 3.86 | 36 |
| 2012 | 3.82 | 38 |
| 2011 | 3.78 | 42 |
| 2010 | 3.76 | 43 |
| 2009 | 3.72 | 41 |
| 2008 | 3.66 | 47 |
| 2007 | 3.62 | 51 |
| 2006 | 3.54 | 56 |
| 2005 | 3.43 | 54 |
| 2004 | 3.31 | 60 |
| 2003 | 3.25 | 60 |
| 2002 | 3.28 | 61 |
| 2001 | 3.37 | 60 |
| 2000 | 3.56 | 53 |
| 1999 | 4.08 | 33 |
| 1998 | 5.75 | 9 |
| 1997 | 5.36 | 10 |
| 1996 | 4.73 | 18 |
| 1995 | 3.86 | 49 |
| 1994 | 3.16 | 70 |
| 1993 | 3.01 | 80 |
| 1992 | 3.68 | 60 |
| 1991 | 4.91 | 33 |
| 1990 | 6.48 | 11 |
| 1989 | 7.95 | 3 |
| 1988 | 8.89 | 2 |
| 1987 | 8.58 | 2 |
| 1986 | 7.89 | 6 |