| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 9.18 | 73 |
| 2015 | 8.61 | 73 |
| 2014 | 8.12 | 74 |
| 2013 | 7.69 | 76 |
| 2012 | 7.32 | 79 |
| 2011 | 7.03 | 80 |
| 2010 | 6.82 | 81 |
| 2009 | 6.79 | 82 |
| 2008 | 6.85 | 81 |
| 2007 | 6.95 | 76 |
| 2006 | 7.04 | 75 |
| 2005 | 7.1 | 73 |
| 2004 | 7.13 | 72 |
| 2003 | 7.18 | 71 |
| 2002 | 7.23 | 68 |
| 2001 | 7.3 | 66 |
| 2000 | 7.38 | 63 |
| 1999 | 7.36 | 62 |
| 1998 | 7.32 | 61 |
| 1997 | 7.28 | 62 |
| 1996 | 7.23 | 61 |
| 1995 | 7.17 | 62 |
| 1994 | 7.04 | 61 |
| 1993 | 6.91 | 62 |
| 1992 | 6.78 | 61 |
| 1991 | 6.65 | 61 |
| 1990 | 6.52 | 61 |
| 1989 | 6.64 | 59 |
| 1988 | 6.78 | 55 |
| 1987 | 6.94 | 53 |
| 1986 | 7.12 | 52 |