| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 9.47 | 95 |
| 2015 | 9.29 | 95 |
| 2014 | 9.19 | 95 |
| 2013 | 9.12 | 97 |
| 2012 | 9.09 | 97 |
| 2011 | 9.04 | 100 |
| 2010 | 8.97 | 100 |
| 2009 | 8.92 | 100 |
| 2008 | 8.87 | 98 |
| 2007 | 8.81 | 97 |
| 2006 | 8.76 | 98 |
| 2005 | 8.71 | 97 |
| 2004 | 8.61 | 96 |
| 2003 | 8.5 | 97 |
| 2002 | 8.38 | 96 |
| 2001 | 8.27 | 95 |
| 2000 | 8.16 | 95 |
| 1999 | 8.11 | 96 |
| 1998 | 8.02 | 96 |
| 1997 | 7.9 | 96 |
| 1996 | 7.74 | 94 |
| 1995 | 7.56 | 94 |
| 1994 | 7.42 | 87 |
| 1993 | 7.28 | 87 |
| 1992 | 7.17 | 84 |
| 1991 | 7.05 | 84 |
| 1990 | 6.91 | 82 |
| 1989 | 6.69 | 75 |
| 1988 | 6.43 | 62 |
| 1987 | 6.13 | 55 |
| 1986 | 5.86 | 44 |