| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 25.21 | 53 |
| 2014 | 25.85 | 49 |
| 2013 | 26.99 | 57 |
| 2012 | 26.69 | 56 |
| 2011 | 25.91 | 59 |
| 2010 | 26.4 | 53 |
| 2009 | 27.57 | 47 |
| 2008 | 26.44 | 56 |
| 2007 | 29.83 | 46 |
| 2006 | 27.5 | 50 |
| 2005 | 29.06 | 43 |
| 2004 | 29.32 | 39 |
| 2003 | 28.29 | 41 |
| 2002 | 31.1 | 34 |
| 2001 | 33.66 | 29 |
| 2000 | 32.83 | 28 |
| 1999 | 33.9 | 29 |
| 1998 | 34.15 | 30 |
| 1997 | 34.02 | 30 |
| 1996 | 32.43 | 28 |
| 1995 | 29.97 | 31 |
| 1994 | 28.7 | 31 |
| 1993 | 23.81 | 39 |
| 1992 | 20.83 | 41 |
| 1991 | 22.26 | 35 |
| 1990 | 21.22 | 37 |
| 1989 | 19.72 | 41 |
| 1988 | 18.67 | 43 |
| 1987 | 18.23 | 46 |
| 1986 | 20.03 | 39 |