| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.04 | 86 |
| 2015 | 7.84 | 86 |
| 2014 | 7.69 | 84 |
| 2013 | 7.62 | 84 |
| 2012 | 7.6 | 83 |
| 2011 | 7.6 | 87 |
| 2010 | 7.58 | 88 |
| 2009 | 7.52 | 86 |
| 2008 | 7.44 | 82 |
| 2007 | 7.34 | 79 |
| 2006 | 7.24 | 79 |
| 2005 | 7.15 | 78 |
| 2004 | 7.07 | 77 |
| 2003 | 7 | 76 |
| 2002 | 6.93 | 76 |
| 2001 | 6.86 | 75 |
| 2000 | 6.79 | 75 |
| 1999 | 6.75 | 70 |
| 1998 | 6.71 | 70 |
| 1997 | 6.67 | 67 |
| 1996 | 6.63 | 66 |
| 1995 | 6.57 | 65 |
| 1994 | 6.53 | 64 |
| 1993 | 6.48 | 63 |
| 1992 | 6.42 | 60 |
| 1991 | 6.35 | 62 |
| 1990 | 6.28 | 60 |
| 1989 | 6.2 | 52 |
| 1988 | 6.13 | 51 |
| 1987 | 6.04 | 48 |
| 1986 | 5.96 | 50 |