| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 27.11 | 70 |
| 2015 | 25.65 | 92 |
| 2014 | 26.19 | 91 |
| 2013 | 25.76 | 97 |
| 2012 | 28.42 | 76 |
| 2011 | 29.08 | 73 |
| 2010 | 29.29 | 67 |
| 2009 | 29.62 | 63 |
| 2008 | 33.62 | 54 |
| 2007 | 36.73 | 40 |
| 2006 | 36.12 | 43 |
| 2005 | 32.35 | 56 |
| 2004 | 35.88 | 38 |
| 2003 | 34.59 | 42 |
| 2002 | 34.53 | 39 |
| 2001 | 34.7 | 41 |
| 2000 | 36.32 | 33 |
| 1999 | 38.51 | 18 |
| 1998 | 36.13 | 22 |
| 1997 | 35.1 | 30 |
| 1996 | 38.2 | 24 |
| 1995 | 42.68 | 13 |
| 1994 | 47.52 | 8 |
| 1993 | 37.69 | 29 |
| 1992 | 50.91 | 9 |
| 1991 | 50.49 | 8 |
| 1990 | 44.57 | 18 |
| 1989 | 48.37 | 9 |
| 1988 | 47.69 | 8 |
| 1987 | 47.09 | 8 |