| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.21 | 54 |
| 2015 | 6.1 | 54 |
| 2014 | 6.04 | 53 |
| 2013 | 5.99 | 48 |
| 2012 | 5.96 | 45 |
| 2011 | 5.92 | 45 |
| 2010 | 5.87 | 43 |
| 2009 | 5.85 | 43 |
| 2008 | 5.82 | 42 |
| 2007 | 5.78 | 42 |
| 2006 | 5.74 | 40 |
| 2005 | 5.69 | 38 |
| 2004 | 5.67 | 38 |
| 2003 | 5.65 | 35 |
| 2002 | 5.62 | 31 |
| 2001 | 5.58 | 30 |
| 2000 | 5.53 | 29 |
| 1999 | 5.53 | 29 |
| 1998 | 5.52 | 29 |
| 1997 | 5.5 | 29 |
| 1996 | 5.47 | 28 |
| 1995 | 5.43 | 27 |
| 1994 | 5.44 | 25 |
| 1993 | 5.43 | 23 |
| 1992 | 5.41 | 22 |
| 1991 | 5.38 | 24 |
| 1990 | 5.33 | 25 |
| 1989 | 5.33 | 23 |
| 1988 | 5.32 | 24 |
| 1987 | 5.3 | 24 |
| 1986 | 5.27 | 24 |