| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.33 | 60 |
| 2015 | 6.37 | 62 |
| 2014 | 6.4 | 65 |
| 2013 | 6.4 | 65 |
| 2012 | 6.38 | 66 |
| 2011 | 6.35 | 65 |
| 2010 | 6.31 | 62 |
| 2009 | 6.26 | 62 |
| 2008 | 6.21 | 61 |
| 2007 | 6.17 | 59 |
| 2006 | 6.13 | 59 |
| 2005 | 6.08 | 58 |
| 2004 | 6.03 | 54 |
| 2003 | 5.98 | 51 |
| 2002 | 5.93 | 50 |
| 2001 | 5.87 | 44 |
| 2000 | 5.8 | 42 |
| 1999 | 5.74 | 36 |
| 1998 | 5.67 | 33 |
| 1997 | 5.6 | 31 |
| 1996 | 5.52 | 31 |
| 1995 | 5.45 | 28 |
| 1994 | 5.47 | 27 |
| 1993 | 5.45 | 25 |
| 1992 | 5.39 | 21 |
| 1991 | 5.3 | 20 |
| 1990 | 5.17 | 17 |
| 1989 | 5.19 | 19 |
| 1988 | 5.18 | 19 |
| 1987 | 5.14 | 18 |
| 1986 | 5.08 | 18 |