| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.51 | 82 |
| 2015 | 5.36 | 100 |
| 2014 | 5.63 | 102 |
| 2013 | 5.51 | 105 |
| 2012 | 5.91 | 100 |
| 2011 | 6.4 | 100 |
| 2010 | 7.19 | 96 |
| 2009 | 7.74 | 94 |
| 2008 | 7.81 | 93 |
| 2007 | 8.87 | 89 |
| 2006 | 9.38 | 87 |
| 2005 | 9.56 | 88 |
| 2004 | 9.79 | 90 |
| 2003 | 9.78 | 89 |
| 2002 | 9.36 | 87 |
| 2001 | 9.32 | 91 |
| 2000 | 10.26 | 87 |
| 1999 | 12.26 | 79 |
| 1998 | 13.86 | 76 |
| 1997 | 13.78 | 77 |
| 1996 | 13.37 | 80 |
| 1995 | 14.02 | 79 |
| 1994 | 13.5 | 78 |
| 1993 | 12.93 | 76 |
| 1992 | 13.11 | 76 |
| 1991 | 13.02 | 79 |
| 1990 | 12.27 | 83 |
| 1989 | 12.42 | 76 |
| 1988 | 13.03 | 75 |
| 1987 | 13.5 | 69 |
| 1986 | 13.2 | 68 |