| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.648 | 77 |
| 2014 | 7.291 | 97 |
| 2013 | 7.622 | 98 |
| 2012 | 8.185 | 98 |
| 2011 | 10.156 | 74 |
| 2010 | 9.788 | 80 |
| 2009 | 8.589 | 101 |
| 2008 | 8.646 | 104 |
| 2007 | 7.704 | 123 |
| 2006 | 7.892 | 117 |
| 2005 | 8.472 | 103 |
| 2004 | 9.552 | 97 |
| 2003 | 6.786 | 122 |
| 2002 | 7.413 | 119 |
| 2001 | 8.585 | 114 |
| 2000 | 12.317 | 84 |
| 1999 | 15 | 76 |
| 1998 | 18.558 | 61 |
| 1997 | 18.917 | 57 |
| 1996 | 20.958 | 53 |
| 1995 | 23.05 | 39 |
| 1994 | 27.442 | 27 |
| 1993 | 28.558 | 31 |
| 1992 | 28.708 | 18 |
| 1991 | 29.45 | 21 |
| 1990 | 27.618 | 18 |
| 1989 | 23.263 | 17 |
| 1988 | 22.892 | 16 |
| 1987 | 21.821 | 15 |
| 1986 | 20.5 | 13 |