| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 0.67 | 131 |
| 2014 | 0.75 | 131 |
| 2013 | 0.75 | 132 |
| 2012 | 0.78 | 130 |
| 2011 | 0.79 | 121 |
| 2010 | 0.82 | 123 |
| 2009 | 0.84 | 124 |
| 2008 | 0.88 | 126 |
| 2007 | 0.91 | 119 |
| 2006 | 0.79 | 123 |
| 2005 | 0.85 | 129 |
| 2004 | 0.89 | 129 |
| 2003 | 0.91 | 126 |
| 2002 | 0.88 | 125 |
| 2001 | 0.91 | 122 |
| 2000 | 0.98 | 117 |
| 1999 | 0.98 | 115 |
| 1998 | 0.99 | 115 |
| 1997 | 1.02 | 116 |
| 1996 | 1.04 | 115 |
| 1995 | 1.06 | 113 |
| 1994 | 1.1 | 116 |
| 1993 | 1.11 | 118 |
| 1992 | 1.1 | 109 |
| 1991 | 1.15 | 103 |
| 1990 | 1.19 | 102 |
| 1989 | 1.22 | 98 |
| 1988 | 1.29 | 94 |