| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2012 | 36 | 81 |
| 2011 | 33 | 78 |
| 2010 | 25 | 82 |
| 2009 | 22 | 83 |
| 2008 | 24 | 85 |
| 2007 | 17 | 92 |
| 2006 | 12 | 99 |
| 2005 | 12 | 94 |
| 2004 | 9 | 90 |
| 2003 | 7 | 95 |
| 2002 | 6 | 98 |
| 2001 | 5 | 94 |
| 2000 | 5 | 94 |
| 1999 | 5 | 93 |
| 1998 | 4 | 94 |
| 1997 | 4 | 97 |
| 1996 | 3 | 98 |
| 1995 | 3 | 93 |
| 1994 | 3 | 93 |
| 1993 | 3 | 89 |
| 1992 | 4 | 79 |
| 1991 | 3 | 85 |
| 1990 | 3 | 80 |
| 1989 | 3 | 78 |
| 1988 | 3 | 72 |
| 1987 | 3 | 73 |
| 1986 | 3 | 75 |