| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2014 | 14.74 | 103 |
| 2013 | 27.93 | 54 |
| 2012 | 27.36 | 54 |
| 2011 | 26.33 | 56 |
| 2010 | 31.57 | 44 |
| 2009 | 24.99 | 57 |
| 2008 | 27.65 | 49 |
| 2007 | 36.24 | 38 |
| 2006 | 34.7 | 38 |
| 2005 | 32.53 | 34 |
| 2004 | 33.52 | 33 |
| 2003 | 34 | 33 |
| 2002 | 33.27 | 31 |
| 2001 | 30.74 | 33 |
| 2000 | 28.82 | 34 |
| 1999 | 28.05 | 36 |
| 1998 | 29.34 | 33 |
| 1997 | 26.75 | 35 |
| 1996 | 23.48 | 39 |
| 1995 | 20.78 | 51 |
| 1994 | 15.33 | 75 |
| 1993 | 22.34 | 44 |
| 1992 | 23.19 | 36 |
| 1991 | 21.39 | 36 |
| 1990 | 18.9 | 48 |
| 1989 | 16.26 | 54 |
| 1988 | 15.25 | 56 |
| 1987 | 15.11 | 53 |
| 1986 | 14.17 | 54 |