| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 12.35 | 105 |
| 2014 | 12.93 | 115 |
| 2013 | 11.28 | 139 |
| 2012 | 9.66 | 145 |
| 2011 | 8.7 | 152 |
| 2010 | 9.63 | 148 |
| 2009 | 12.03 | 133 |
| 2008 | 12.56 | 131 |
| 2007 | 11.95 | 139 |
| 2006 | 9.71 | 143 |
| 2005 | 10.03 | 142 |
| 2004 | 11.63 | 121 |
| 2003 | 10.08 | 126 |
| 2002 | 8.96 | 137 |
| 2001 | 10.45 | 126 |
| 2000 | 12.85 | 98 |
| 1999 | 17.23 | 70 |
| 1998 | 15.68 | 76 |
| 1997 | 22.17 | 48 |
| 1996 | 22.12 | 44 |
| 1995 | 22.55 | 39 |
| 1994 | 21.54 | 47 |
| 1993 | 15.98 | 66 |
| 1992 | 14.67 | 68 |
| 1991 | 10.81 | 84 |
| 1990 | 10.25 | 82 |
| 1989 | 9.95 | 80 |
| 1988 | 10.74 | 75 |
| 1987 | 11.8 | 66 |
| 1986 | 10.18 | 74 |