| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.986 | 86 |
| 2015 | 6.601 | 97 |
| 2014 | 7.775 | 92 |
| 2013 | 8.413 | 93 |
| 2012 | 8.139 | 99 |
| 2011 | 7.803 | 98 |
| 2010 | 6.256 | 115 |
| 2009 | 6.119 | 120 |
| 2008 | 8.353 | 108 |
| 2007 | 7.915 | 121 |
| 2006 | 7.639 | 122 |
| 2005 | 7.574 | 113 |
| 2004 | 7.654 | 110 |
| 2003 | 9.184 | 100 |
| 1999 | 5.189 | 145 |
| 1998 | 7.24 | 129 |
| 1997 | 9.15 | 116 |
| 1996 | 11.733 | 97 |
| 1995 | 13.8 | 83 |
| 1994 | 15.008 | 64 |
| 1993 | 16.475 | 55 |
| 1992 | 20.433 | 33 |
| 1991 | 25.017 | 26 |
| 1990 | 21.775 | 24 |
| 1989 | 19.587 | 26 |
| 1988 | 17.53 | 23 |
| 1987 | 18.917 | 19 |
| 1986 | 19.625 | 15 |