| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 21.53 | 98 |
| 2015 | 22.1 | 115 |
| 2014 | 22.06 | 113 |
| 2013 | 22.69 | 115 |
| 2012 | 23.98 | 107 |
| 2011 | 24.46 | 104 |
| 2010 | 25.36 | 99 |
| 2009 | 25.82 | 96 |
| 2008 | 26.35 | 97 |
| 2007 | 26.76 | 97 |
| 2006 | 26.4 | 98 |
| 2005 | 26.89 | 91 |
| 2004 | 27.29 | 87 |
| 2003 | 26.76 | 91 |
| 2002 | 27.29 | 86 |
| 2001 | 28.05 | 84 |
| 2000 | 28.22 | 79 |
| 1999 | 28.38 | 77 |
| 1998 | 28.53 | 76 |
| 1997 | 28.69 | 81 |
| 1996 | 28.68 | 83 |
| 1995 | 29.17 | 81 |
| 1994 | 29.15 | 66 |
| 1993 | 29.9 | 66 |
| 1992 | 30.71 | 59 |
| 1991 | 29.84 | 68 |
| 1990 | 29.89 | 64 |
| 1989 | 31.59 | 52 |
| 1988 | 31.53 | 48 |
| 1987 | 31.34 | 50 |
| 1986 | 31.93 | 41 |