| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.34 | 69 |
| 2015 | 8.72 | 81 |
| 2014 | 10.07 | 72 |
| 2013 | 11.32 | 66 |
| 2012 | 11.51 | 65 |
| 2011 | 11.59 | 67 |
| 2010 | 10.53 | 72 |
| 2009 | 9.79 | 79 |
| 2008 | 10.08 | 79 |
| 2007 | 9.35 | 86 |
| 2006 | 9.41 | 86 |
| 2005 | 9.2 | 91 |
| 2004 | 9.29 | 93 |
| 2003 | 9.44 | 90 |
| 2002 | 8.7 | 94 |
| 2001 | 8.58 | 96 |
| 2000 | 8.5 | 97 |
| 1999 | 8.9 | 93 |
| 1998 | 10.26 | 88 |
| 1997 | 9.07 | 94 |
| 1996 | 9.07 | 95 |
| 1995 | 9.08 | 96 |
| 1994 | 8.63 | 94 |
| 1993 | 8.03 | 97 |
| 1992 | 12.3 | 80 |
| 1991 | 12.65 | 80 |
| 1990 | 12.5 | 82 |
| 1989 | 15.08 | 67 |
| 1988 | 16.18 | 65 |
| 1987 | 15.73 | 62 |
| 1986 | 15.66 | 61 |