| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 15.79 | 88 |
| 2014 | 13.45 | 113 |
| 2013 | 12.14 | 133 |
| 2012 | 14.18 | 121 |
| 2011 | 12.03 | 137 |
| 2010 | 5.7 | 167 |
| 2009 | 5.99 | 166 |
| 2008 | 4.53 | 172 |
| 2007 | 6.04 | 167 |
| 2006 | 6.41 | 162 |
| 2005 | 9.02 | 147 |
| 2004 | 9.21 | 136 |
| 2003 | 9.38 | 133 |
| 2002 | 11.22 | 121 |
| 2001 | 10.73 | 122 |
| 2000 | 11.56 | 111 |
| 1999 | 13.07 | 97 |
| 1998 | 15.34 | 77 |
| 1997 | 13.95 | 81 |
| 1996 | 11.78 | 94 |
| 1995 | 10.97 | 95 |
| 1994 | 15.46 | 72 |
| 1993 | 17.56 | 60 |
| 1992 | 18.65 | 50 |
| 1991 | 17.7 | 48 |
| 1990 | 15.94 | 58 |
| 1989 | 16.67 | 52 |
| 1988 | 16.13 | 52 |
| 1987 | 14.65 | 55 |
| 1986 | 18.46 | 45 |