| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 28.89 | 63 |
| 2014 | 27.9 | 74 |
| 2013 | 27.1 | 84 |
| 2012 | 26.89 | 86 |
| 2011 | 27.02 | 92 |
| 2010 | 28.51 | 75 |
| 2009 | 27.3 | 83 |
| 2008 | 29.05 | 75 |
| 2007 | 29.87 | 75 |
| 2006 | 29.97 | 71 |
| 2005 | 30.11 | 66 |
| 2004 | 30.28 | 66 |
| 2003 | 30.39 | 63 |
| 2002 | 30.54 | 65 |
| 2001 | 31.41 | 58 |
| 2000 | 32.71 | 52 |
| 1999 | 32.91 | 43 |
| 1998 | 33.51 | 38 |
| 1997 | 34.15 | 34 |
| 1996 | 34.68 | 36 |
| 1995 | 34.66 | 36 |
| 1994 | 34.82 | 36 |
| 1993 | 34.51 | 39 |
| 1992 | 35.87 | 39 |
| 1991 | 37.01 | 33 |
| 1990 | 37.36 | 32 |
| 1989 | 37.1 | 29 |
| 1988 | 36.95 | 28 |
| 1987 | 36.66 | 28 |
| 1986 | 37.1 | 24 |