| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.313 | 85 |
| 2015 | 6.563 | 98 |
| 2014 | 6.772 | 101 |
| 2013 | 6.958 | 103 |
| 2012 | 7.098 | 104 |
| 2011 | 6.914 | 104 |
| 2010 | 5.935 | 120 |
| 2009 | 5.963 | 124 |
| 2008 | 7.042 | 123 |
| 2007 | 7.05 | 132 |
| 2006 | 7.354 | 128 |
| 2005 | 5.792 | 135 |
| 2004 | 5.5 | 141 |
| 2003 | 5.938 | 131 |
| 2002 | 6.875 | 125 |
| 2001 | 7.25 | 128 |
| 2000 | 7.833 | 126 |
| 1999 | 8.979 | 118 |
| 1998 | 14.417 | 81 |
| 1997 | 13.646 | 86 |
| 1996 | 13.396 | 86 |
| 1995 | 13.25 | 84 |
| 1994 | 10.896 | 88 |
| 1993 | 11.167 | 86 |
| 1992 | 12.167 | 76 |
| 1991 | 15.396 | 53 |
| 1990 | 14.417 | 52 |
| 1989 | 12.25 | 66 |
| 1988 | 11.583 | 63 |
| 1987 | 11.542 | 59 |
| 1986 | 13.375 | 47 |