| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.28 | 65 |
| 2015 | 9.39 | 123 |
| 2014 | 9.98 | 129 |
| 2013 | 9.82 | 146 |
| 2012 | 9.87 | 144 |
| 2011 | 9.98 | 150 |
| 2010 | 11.31 | 138 |
| 2009 | 11.18 | 137 |
| 2008 | 10.63 | 144 |
| 2007 | 11.06 | 142 |
| 2006 | 10.91 | 138 |
| 2005 | 10.13 | 140 |
| 2004 | 10.2 | 130 |
| 2003 | 11.92 | 115 |
| 2002 | 12.31 | 111 |
| 2001 | 12.64 | 110 |
| 2000 | 10.23 | 123 |
| 1999 | 9.71 | 123 |
| 1998 | 8.85 | 123 |
| 1997 | 8.16 | 127 |
| 1996 | 8.9 | 119 |
| 1995 | 10.42 | 99 |
| 1994 | 10.34 | 100 |
| 1993 | 10.93 | 96 |
| 1992 | 10.91 | 87 |
| 1991 | 8.67 | 96 |
| 1990 | 9.67 | 85 |
| 1989 | 8.02 | 96 |
| 1988 | 6.55 | 104 |
| 1987 | 5.9 | 106 |
| 1986 | 4.06 | 108 |