| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 7.53 | 130 |
| 2014 | 6.82 | 144 |
| 2013 | 6.89 | 158 |
| 2012 | 7.13 | 157 |
| 2011 | 6.79 | 162 |
| 2010 | 7.34 | 157 |
| 2009 | 7.26 | 159 |
| 2008 | 5.87 | 165 |
| 2007 | 7.02 | 160 |
| 2006 | 6.89 | 159 |
| 2005 | 7.16 | 155 |
| 2004 | 6.66 | 149 |
| 2003 | 8.21 | 137 |
| 2002 | 9.03 | 136 |
| 2001 | 8.11 | 136 |
| 2000 | 7.69 | 133 |
| 1999 | 8.3 | 129 |
| 1998 | 9.24 | 118 |
| 1997 | 9.42 | 112 |
| 1996 | 9.52 | 113 |
| 1995 | 10.87 | 96 |
| 1994 | 12.95 | 80 |
| 1993 | 14.23 | 75 |
| 1992 | 11.58 | 83 |
| 1991 | 12.79 | 71 |
| 1990 | 14.97 | 63 |
| 1989 | 15.18 | 58 |
| 1988 | 14.62 | 59 |
| 1987 | 11.34 | 70 |
| 1986 | 11.88 | 64 |