| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2013 | 24.51 | 63 |
| 2012 | 25.8 | 58 |
| 2011 | 25.02 | 60 |
| 2010 | 25.64 | 57 |
| 2009 | 24.25 | 59 |
| 2008 | 30.55 | 43 |
| 2007 | 29.63 | 48 |
| 2006 | 26.46 | 55 |
| 2005 | 22.94 | 63 |
| 2004 | 25.29 | 53 |
| 2003 | 17.91 | 74 |
| 2002 | 29.31 | 39 |
| 2001 | 21.91 | 56 |
| 2000 | 23.95 | 49 |
| 1999 | 21.32 | 54 |
| 1998 | 20.61 | 56 |
| 1997 | 19.74 | 58 |
| 1996 | 17.72 | 65 |
| 1995 | 22.24 | 44 |
| 1994 | 19.78 | 55 |
| 1993 | 15.99 | 65 |
| 1992 | 15.24 | 64 |
| 1991 | 14.97 | 62 |
| 1990 | 12.83 | 70 |
| 1989 | 14.47 | 62 |
| 1988 | 15.09 | 57 |
| 1987 | 12.56 | 60 |
| 1986 | 8.6 | 87 |