| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2014 | 8.2 | 179 |
| 2013 | 8.3 | 182 |
| 2012 | 8 | 183 |
| 2011 | 8.4 | 184 |
| 2010 | 7.4 | 184 |
| 2009 | 6.5 | 185 |
| 2008 | 6.8 | 183 |
| 2007 | 5.6 | 185 |
| 2006 | 4.7 | 184 |
| 2005 | 4.3 | 184 |
| 2004 | 3.9 | 185 |
| 2003 | 3.3 | 184 |
| 2002 | 2.8 | 182 |
| 2001 | 2.9 | 177 |
| 2000 | 3 | 177 |
| 1999 | 3.1 | 173 |
| 1998 | 2.9 | 173 |
| 1997 | 2.5 | 177 |
| 1996 | 2.6 | 175 |
| 1995 | 2.5 | 175 |
| 1994 | 2.4 | 168 |
| 1993 | 2.1 | 163 |
| 1992 | 2.2 | 161 |
| 1991 | 2.2 | 158 |
| 1990 | 2 | 156 |
| 1989 | 1.8 | 137 |
| 1988 | 1.9 | 132 |
| 1987 | 1.7 | 132 |
| 1986 | 1.5 | 133 |