| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.9 | 118 |
| 2015 | 8.92 | 116 |
| 2014 | 8.96 | 116 |
| 2013 | 9.05 | 116 |
| 2012 | 9.13 | 117 |
| 2011 | 9.2 | 119 |
| 2010 | 9.26 | 123 |
| 2009 | 9.3 | 120 |
| 2008 | 9.32 | 133 |
| 2007 | 9.34 | 135 |
| 2006 | 9.34 | 127 |
| 2005 | 9.34 | 120 |
| 2004 | 9.33 | 113 |
| 2003 | 9.32 | 111 |
| 2002 | 9.31 | 110 |
| 2001 | 9.29 | 116 |
| 2000 | 9.28 | 111 |
| 1999 | 9.28 | 109 |
| 1998 | 9.28 | 108 |
| 1997 | 9.28 | 108 |
| 1996 | 9.3 | 105 |
| 1995 | 8.94 | 110 |
| 1994 | 8.9 | 108 |
| 1993 | 8.94 | 107 |
| 1992 | 8.84 | 105 |
| 1991 | 8.98 | 109 |