| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.04 | 77 |
| 2015 | 1.52 | 131 |
| 2014 | 3.33 | 137 |
| 2013 | 4.32 | 130 |
| 2012 | 7.23 | 101 |
| 2011 | 9.99 | 87 |
| 2010 | 8.59 | 109 |
| 2009 | 11.34 | 79 |
| 2008 | 12.05 | 101 |
| 2007 | 13.41 | 111 |
| 2006 | 19.37 | 76 |
| 2005 | 6.19 | 141 |
| 2004 | 6.24 | 132 |
| 2003 | 8.05 | 112 |
| 2002 | -.33 | 146 |
| 2001 | 5.86 | 125 |
| 2000 | -2.05 | 153 |
| 1999 | 8.51 | 113 |
| 1998 | 30.25 | 16 |
| 1997 | 10.27 | 101 |
| 1996 | 9.79 | 103 |
| 1995 | 8.5 | 109 |
| 1994 | 14.43 | 86 |
| 1993 | 8.45 | 91 |
| 1992 | 8.9 | 89 |
| 1991 | 12.45 | 80 |
| 1990 | 19.98 | 48 |
| 1989 | 22.47 | 39 |
| 1988 | 13.48 | 78 |
| 1987 | 19.82 | 46 |
| 1986 | 9.98 | 78 |