| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 0.3 | 173 |
| 2014 | 0.3 | 176 |
| 2013 | 0.3 | 168 |
| 2012 | 0.9 | 161 |
| 2011 | 0.9 | 159 |
| 2010 | 1.4 | 145 |
| 2009 | 0.7 | 152 |
| 2008 | 1.1 | 155 |
| 2007 | 0.4 | 173 |
| 2006 | 1.2 | 143 |
| 2005 | -.5 | 188 |
| 2004 | 0.7 | 136 |
| 2003 | -.6 | 186 |
| 2002 | 0.9 | 114 |
| 2001 | 0.3 | 135 |
| 2000 | 0.9 | 114 |
| 1999 | 1 | 106 |
| 1998 | 1.5 | 101 |
| 1997 | -.2 | 180 |
| 1996 | 0.2 | 127 |
| 1995 | 0.5 | 102 |
| 1994 | 0.6 | 90 |
| 1993 | 0.7 | 85 |
| 1992 | 0.9 | 70 |
| 1991 | 0.8 | 63 |
| 1990 | 0.3 | 84 |
| 1989 | 0.7 | 56 |
| 1988 | 0.5 | 60 |
| 1987 | 0.6 | 55 |
| 1986 | 0.3 | 53 |