| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 21.02 | 8 |
| 2015 | 21.29 | 12 |
| 2014 | 21.67 | 20 |
| 2013 | 22.09 | 26 |
| 2012 | 22.53 | 29 |
| 2011 | 23.02 | 30 |
| 2010 | 23.55 | 32 |
| 2009 | 24.24 | 33 |
| 2008 | 24.9 | 33 |
| 2007 | 25.47 | 33 |
| 2006 | 25.93 | 34 |
| 2005 | 26.36 | 34 |
| 2004 | 26.96 | 33 |
| 2003 | 27.59 | 34 |
| 2002 | 28.29 | 34 |
| 2001 | 29.15 | 35 |
| 2000 | 30.14 | 35 |
| 1999 | 30.63 | 35 |
| 1998 | 31.21 | 36 |
| 1997 | 31.65 | 35 |
| 1996 | 31.68 | 32 |
| 1995 | 31.15 | 28 |
| 1994 | 30.92 | 27 |
| 1993 | 30.36 | 25 |
| 1992 | 29.73 | 23 |
| 1991 | 29.36 | 19 |
| 1990 | 29.42 | 16 |
| 1989 | 29.99 | 16 |
| 1988 | 31 | 18 |
| 1987 | 32.29 | 23 |
| 1986 | 33.52 | 27 |