| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.74 | 92 |
| 2015 | 6.64 | 85 |
| 2014 | 6.44 | 81 |
| 2013 | 6.44 | 79 |
| 2012 | 6.36 | 75 |
| 2011 | 6.47 | 72 |
| 2010 | 6.49 | 67 |
| 2009 | 6.51 | 71 |
| 2008 | 6.53 | 88 |
| 2007 | 6.59 | 86 |
| 2006 | 6.68 | 78 |
| 2005 | 7.8 | 98 |
| 2004 | 7.72 | 90 |
| 2003 | 7.64 | 85 |
| 2002 | 7.57 | 88 |
| 2001 | 7.49 | 89 |
| 2000 | 7.41 | 88 |
| 1999 | 7.34 | 85 |
| 1998 | 6.8 | 73 |
| 1997 | 6.87 | 81 |
| 1996 | 6.92 | 79 |
| 1995 | 6.97 | 79 |
| 1994 | 6.64 | 73 |
| 1993 | 6.91 | 86 |
| 1992 | 6.68 | 79 |
| 1991 | 6.89 | 87 |