| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.88 | 71 |
| 2015 | 6.17 | 135 |
| 2014 | 6.41 | 146 |
| 2013 | 6.35 | 162 |
| 2012 | 6.31 | 161 |
| 2011 | 6 | 166 |
| 2010 | 5.71 | 166 |
| 2009 | 6.53 | 162 |
| 2008 | 8.29 | 151 |
| 2007 | 8.22 | 151 |
| 2006 | 8.42 | 149 |
| 2005 | 12.31 | 129 |
| 2004 | 13.08 | 108 |
| 2003 | 9.67 | 130 |
| 2002 | 12.12 | 112 |
| 2001 | 13.33 | 101 |
| 2000 | 12.64 | 103 |
| 1999 | 12.12 | 106 |
| 1998 | 17.36 | 65 |
| 1997 | 10.91 | 101 |
| 1996 | 9.56 | 112 |
| 1995 | 9.4 | 111 |
| 1994 | 9.17 | 106 |
| 1993 | 8.74 | 108 |
| 1992 | 8.98 | 99 |
| 1991 | 8.05 | 106 |
| 1990 | 8.05 | 99 |
| 1989 | 7.74 | 98 |
| 1988 | 7.09 | 101 |
| 1987 | 7.25 | 96 |
| 1986 | 6.38 | 101 |