| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.87 | 96 |
| 2015 | 6.76 | 89 |
| 2014 | 6.63 | 87 |
| 2013 | 6.21 | 75 |
| 2012 | 6.72 | 81 |
| 2011 | 6.74 | 79 |
| 2010 | 6.75 | 74 |
| 2009 | 6.75 | 79 |
| 2008 | 6.77 | 94 |
| 2007 | 6.81 | 91 |
| 2006 | 6.82 | 86 |
| 2005 | 6.8 | 72 |
| 2004 | 6.79 | 74 |
| 2003 | 6.67 | 70 |
| 2002 | 6.75 | 74 |
| 2001 | 6.74 | 73 |
| 2000 | 6.71 | 77 |
| 1999 | 6.77 | 72 |
| 1998 | 6.76 | 72 |
| 1997 | 6.8 | 77 |
| 1996 | 6.61 | 68 |
| 1995 | 6.75 | 75 |
| 1994 | 6.82 | 79 |
| 1993 | 6.69 | 80 |
| 1992 | 6.67 | 78 |
| 1991 | 6.69 | 82 |