| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.19 | 73 |
| 2015 | 7.08 | 75 |
| 2014 | 6.95 | 72 |
| 2013 | 6.88 | 72 |
| 2012 | 6.86 | 73 |
| 2011 | 6.86 | 75 |
| 2010 | 6.82 | 73 |
| 2009 | 6.58 | 70 |
| 2008 | 6.32 | 65 |
| 2007 | 6.08 | 53 |
| 2006 | 5.91 | 49 |
| 2005 | 5.81 | 45 |
| 2004 | 5.83 | 45 |
| 2003 | 5.87 | 46 |
| 2002 | 5.92 | 48 |
| 2001 | 5.98 | 52 |
| 2000 | 6.06 | 52 |
| 1999 | 6.16 | 53 |
| 1998 | 6.27 | 55 |
| 1997 | 6.37 | 60 |
| 1996 | 6.44 | 62 |
| 1995 | 6.49 | 63 |
| 1994 | 6.56 | 65 |
| 1993 | 6.63 | 66 |
| 1992 | 6.7 | 70 |
| 1991 | 6.77 | 75 |
| 1990 | 6.83 | 80 |
| 1989 | 6.73 | 77 |
| 1988 | 6.62 | 76 |
| 1987 | 6.53 | 70 |
| 1986 | 6.45 | 68 |