| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 20.42 | 7 |
| 2015 | 20.74 | 7 |
| 2014 | 20.88 | 8 |
| 2013 | 21.28 | 15 |
| 2012 | 21.81 | 23 |
| 2011 | 22.22 | 26 |
| 2010 | 22.39 | 26 |
| 2009 | 23.03 | 30 |
| 2008 | 23.55 | 30 |
| 2007 | 24.03 | 29 |
| 2006 | 24.72 | 29 |
| 2005 | 25.74 | 28 |
| 2004 | 26.65 | 32 |
| 2003 | 27.71 | 35 |
| 2002 | 28.81 | 39 |
| 2001 | 29.71 | 37 |
| 2000 | 30.31 | 36 |
| 1999 | 30.79 | 36 |
| 1998 | 31.09 | 35 |
| 1997 | 31.31 | 33 |
| 1996 | 31.6 | 31 |
| 1995 | 32.01 | 31 |
| 1994 | 32.36 | 31 |
| 1993 | 32.88 | 31 |
| 1992 | 33.49 | 32 |
| 1991 | 34.15 | 34 |
| 1990 | 34.89 | 36 |
| 1989 | 35.5 | 36 |
| 1988 | 36.15 | 36 |
| 1987 | 36.86 | 38 |
| 1986 | 37.63 | 40 |