| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.36 | 75 |
| 2015 | 6.24 | 96 |
| 2014 | 7.44 | 99 |
| 2013 | 11.41 | 71 |
| 2012 | 6.3 | 110 |
| 2011 | 4.58 | 127 |
| 2010 | 5.41 | 130 |
| 2009 | 3.46 | 126 |
| 2008 | 7.57 | 129 |
| 2007 | 10.74 | 133 |
| 2006 | 18.03 | 83 |
| 2005 | 15.78 | 77 |
| 2004 | 10.58 | 100 |
| 2003 | 8.6 | 108 |
| 2002 | 14.22 | 69 |
| 2001 | 9.72 | 104 |
| 2000 | 13 | 80 |
| 1999 | 16.78 | 61 |
| 1998 | 1.97 | 131 |
| 1997 | 9.91 | 103 |
| 1996 | 11.79 | 92 |
| 1995 | 14.01 | 82 |
| 1994 | 12.23 | 96 |
| 1993 | 89.63 | 10 |
| 1992 | 29.88 | 37 |
| 1991 | 9.37 | 88 |
| 1990 | 11.15 | 75 |
| 1989 | 9.52 | 89 |
| 1988 | 6.3 | 99 |
| 1987 | 1.49 | 112 |
| 1986 | 15 | 59 |