| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 35.6 | 9 |
| 2015 | 33.3 | 10 |
| 2014 | 30.37 | 16 |
| 2013 | 29.43 | 18 |
| 2012 | 29.12 | 19 |
| 2011 | 29.27 | 18 |
| 2010 | 27.83 | 24 |
| 2009 | 26.14 | 28 |
| 2008 | 24.92 | 31 |
| 2007 | 23.27 | 37 |
| 2006 | 23.16 | 39 |
| 2005 | 27.2 | 31 |
| 2004 | 28.04 | 29 |
| 2003 | 29.03 | 28 |
| 2002 | 29.13 | 28 |
| 2001 | 31.33 | 25 |
| 2000 | 32.36 | 24 |
| 1999 | 32.38 | 28 |
| 1998 | 31.23 | 31 |
| 1997 | 30.91 | 35 |
| 1996 | 30.74 | 35 |
| 1995 | 31.13 | 36 |
| 1994 | 33.32 | 32 |
| 1993 | 31.52 | 33 |
| 1992 | 28.74 | 37 |
| 1991 | 28.14 | 39 |
| 1990 | 29.52 | 35 |
| 1989 | 30.19 | 30 |
| 1988 | 29.89 | 32 |
| 1987 | 31.55 | 26 |
| 1986 | 33.04 | 26 |