| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2014 | 0.66 | 138 |
| 2013 | 0.68 | 134 |
| 2012 | 0.72 | 132 |
| 2011 | 0.5 | 138 |
| 2010 | 0.48 | 141 |
| 2009 | 0.64 | 135 |
| 2008 | 0.49 | 144 |
| 2007 | 0.62 | 132 |
| 2006 | 0.57 | 138 |
| 2005 | 0.63 | 141 |
| 2004 | 0.62 | 142 |
| 2003 | 0.55 | 143 |
| 2002 | 0.57 | 140 |
| 2001 | 0.82 | 127 |
| 2000 | 0.96 | 119 |
| 1999 | 1.04 | 114 |
| 1998 | 1.32 | 100 |
| 1997 | 1.62 | 81 |
| 1996 | 1.53 | 90 |
| 1995 | 1.17 | 109 |
| 1994 | 1.52 | 100 |
| 1993 | 1.38 | 107 |
| 1992 | 1.34 | 105 |
| 1991 | 1.39 | 94 |
| 1990 | 2.13 | 74 |
| 1989 | 1.5 | 89 |
| 1988 | 1.27 | 96 |
| 1987 | 1.35 | 94 |
| 1986 | 1.41 | 87 |