| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 7.2 | 104 |
| 2014 | 7.2 | 103 |
| 2013 | 7 | 102 |
| 2012 | 6.5 | 110 |
| 2011 | 13.1 | 86 |
| 2010 | 4.5 | 113 |
| 2009 | 1.3 | 137 |
| 2008 | 2.8 | 132 |
| 2007 | 1.3 | 152 |
| 2006 | 1.1 | 148 |
| 2005 | 0.8 | 139 |
| 2004 | 0.8 | 135 |
| 2003 | 3.7 | 86 |
| 2002 | 0 | 170 |
| 2001 | 0.1 | 153 |
| 2000 | 0.2 | 145 |
| 1999 | 2.6 | 81 |
| 1998 | 1.9 | 95 |
| 1997 | 2.1 | 83 |
| 1996 | -1.3 | 180 |
| 1995 | 0 | 148 |
| 1994 | 0.2 | 119 |
| 1993 | -.5 | 171 |
| 1992 | -.1 | 159 |
| 1991 | 0.1 | 108 |
| 1990 | 2.3 | 41 |
| 1989 | 6.6 | 30 |
| 1988 | 2.9 | 33 |
| 1987 | 0.4 | 66 |
| 1986 | -.2 | 133 |