| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 11.33 | 45 |
| 2015 | 13.34 | 45 |
| 2014 | 11.01 | 64 |
| 2013 | 13.59 | 59 |
| 2012 | 14.39 | 53 |
| 2011 | 17.32 | 43 |
| 2010 | 18.95 | 47 |
| 2009 | 28.42 | 16 |
| 2008 | 17.78 | 63 |
| 2007 | 16.74 | 93 |
| 2006 | 22.12 | 64 |
| 2005 | 16.74 | 69 |
| 2004 | 14.89 | 73 |
| 2003 | 19.24 | 47 |
| 2002 | 13.14 | 77 |
| 2001 | 15.04 | 77 |
| 2000 | 12.32 | 86 |
| 1999 | 14.67 | 71 |
| 1998 | 14.9 | 55 |
| 1997 | 20.73 | 57 |
| 1996 | 25.27 | 44 |
| 1995 | 29.46 | 38 |
| 1994 | 31.5 | 49 |
| 1993 | 46.67 | 21 |
| 1992 | 30.8 | 34 |
| 1991 | 26.68 | 38 |
| 1990 | 28.87 | 31 |
| 1989 | 18.65 | 54 |
| 1988 | 20.67 | 53 |
| 1987 | 25.34 | 38 |
| 1986 | 30.23 | 20 |