| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.44 | 64 |
| 2015 | 5.29 | 61 |
| 2014 | 6.01 | 74 |
| 2013 | 5.01 | 54 |
| 2012 | 4.85 | 50 |
| 2011 | 5.51 | 62 |
| 2010 | 5.68 | 58 |
| 2009 | 6.51 | 70 |
| 2008 | 5.59 | 68 |
| 2007 | 5.62 | 69 |
| 2006 | 6.7 | 81 |
| 2005 | 5.8 | 65 |
| 2004 | 7.4 | 86 |
| 2003 | 7.9 | 89 |
| 2002 | 10.7 | 124 |
| 2001 | 7.6 | 92 |
| 2000 | 7.6 | 91 |
| 1999 | 6.6 | 69 |
| 1998 | 5.3 | 52 |
| 1997 | 5.4 | 54 |
| 1996 | 8.2 | 94 |
| 1995 | 3.4 | 32 |
| 1994 | 4.41 | 47 |
| 1993 | 5.06 | 55 |
| 1992 | 7.51 | 92 |
| 1991 | 6.33 | 75 |