| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 21.05 | 64 |
| 2014 | 20.41 | 71 |
| 2013 | 23.46 | 66 |
| 2012 | 23.27 | 68 |
| 2011 | 26.15 | 58 |
| 2010 | 22.82 | 66 |
| 2009 | 21.13 | 77 |
| 2008 | 20.3 | 79 |
| 2007 | 21.46 | 75 |
| 2006 | 21.1 | 73 |
| 2005 | 20.22 | 75 |
| 2004 | 20.1 | 67 |
| 2003 | 17.87 | 75 |
| 2002 | 16.15 | 86 |
| 2001 | 15.14 | 88 |
| 2000 | 13.86 | 90 |
| 1999 | 12.63 | 99 |
| 1998 | 14.19 | 86 |
| 1997 | 17.1 | 66 |
| 1996 | 21.67 | 45 |
| 1995 | 19.21 | 60 |
| 1994 | 19.97 | 54 |
| 1993 | 17.26 | 62 |
| 1992 | 19.64 | 48 |
| 1991 | 25.13 | 32 |
| 1990 | 24.14 | 31 |
| 1989 | 23.94 | 32 |
| 1988 | 22.14 | 36 |
| 1987 | 25.25 | 33 |
| 1986 | 26.01 | 30 |