| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.01 | 70 |
| 2015 | 6.89 | 68 |
| 2014 | 6.79 | 69 |
| 2013 | 6.69 | 69 |
| 2012 | 6.59 | 68 |
| 2011 | 6.49 | 66 |
| 2010 | 6.4 | 66 |
| 2009 | 6.34 | 64 |
| 2008 | 6.29 | 63 |
| 2007 | 6.25 | 64 |
| 2006 | 6.22 | 63 |
| 2005 | 6.18 | 63 |
| 2004 | 6.22 | 62 |
| 2003 | 6.26 | 59 |
| 2002 | 6.31 | 59 |
| 2001 | 6.35 | 58 |
| 2000 | 6.38 | 59 |
| 1999 | 6.34 | 57 |
| 1998 | 6.28 | 56 |
| 1997 | 6.18 | 54 |
| 1996 | 6.08 | 50 |
| 1995 | 5.96 | 45 |
| 1994 | 5.86 | 41 |
| 1993 | 5.73 | 36 |
| 1992 | 5.59 | 31 |
| 1991 | 5.42 | 26 |
| 1990 | 5.24 | 21 |
| 1989 | 5.19 | 18 |
| 1988 | 5.13 | 16 |
| 1987 | 5.06 | 16 |
| 1986 | 4.98 | 17 |