| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.6 | 91 |
| 2015 | 0.62 | 92 |
| 2014 | 0.63 | 93 |
| 2013 | 0.61 | 96 |
| 2012 | 0.56 | 97 |
| 2011 | 0.48 | 104 |
| 2010 | 0.4 | 111 |
| 2009 | 0.32 | 117 |
| 2008 | 0.26 | 123 |
| 2007 | 0.23 | 121 |
| 2006 | 0.09 | 131 |
| 2005 | 0.1 | 129 |
| 2004 | 0.11 | 131 |
| 2003 | 0.14 | 130 |
| 2002 | 0.2 | 125 |
| 2001 | 0.27 | 118 |
| 2000 | 0.35 | 114 |
| 1999 | 0.43 | 111 |
| 1998 | 0.55 | 105 |
| 1997 | 0.71 | 100 |
| 1996 | 0.72 | 104 |
| 1995 | 0.9 | 95 |
| 1994 | 1.12 | 84 |
| 1993 | 1.27 | 82 |
| 1992 | 1.3 | 80 |
| 1991 | 1.24 | 86 |
| 1990 | 1.13 | 90 |
| 1989 | 1.04 | 99 |
| 1988 | 1.03 | 97 |
| 1987 | 1.14 | 96 |
| 1986 | 1.69 | 71 |