| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.34 | 133 |
| 2015 | 0.35 | 143 |
| 2014 | 0.47 | 143 |
| 2013 | 0.5 | 143 |
| 2012 | 0.51 | 142 |
| 2011 | 0.54 | 135 |
| 2010 | 0.58 | 135 |
| 2009 | 0.6 | 138 |
| 2008 | 0.58 | 141 |
| 2007 | 0.51 | 141 |
| 2006 | 0.51 | 141 |
| 2005 | 0.54 | 145 |
| 2004 | 0.57 | 144 |
| 2003 | 0.59 | 141 |
| 2002 | 0.63 | 135 |
| 2001 | 0.7 | 132 |
| 2000 | 0.7 | 129 |
| 1999 | 0.75 | 129 |
| 1998 | 0.82 | 124 |
| 1997 | 0.92 | 122 |
| 1996 | 0.99 | 118 |
| 1995 | 1.01 | 115 |
| 1994 | 1.11 | 115 |
| 1993 | 1.14 | 116 |
| 1992 | 1.2 | 107 |
| 1991 | 1.25 | 100 |
| 1990 | 1.2 | 101 |
| 1989 | 1.11 | 102 |
| 1988 | 1.2 | 100 |
| 1987 | 1.28 | 96 |
| 1986 | 1.42 | 86 |