| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2012 | 35 | 52 |
| 2011 | 63.2 | 50 |
| 2010 | 107.5 | 51 |
| 2009 | 294.2 | 39 |
| 2008 | 219.3 | 47 |
| 2007 | 262.8 | 47 |
| 2006 | 135 | 48 |
| 2005 | 41.5 | 52 |
| 2004 | 16.8 | 51 |
| 2003 | 6.9 | 56 |
| 2002 | 5.9 | 57 |
| 2001 | 9.7 | 50 |
| 2000 | 10.9 | 50 |
| 1999 | 25.3 | 47 |
| 1998 | 13.9 | 50 |
| 1997 | 10.5 | 53 |
| 1996 | 4.3 | 55 |
| 1995 | 24.3 | 44 |
| 1994 | 7.9 | 46 |
| 1993 | 5 | 46 |
| 1992 | 0.7 | 51 |
| 1991 | 0.5 | 52 |
| 1990 | 0.6 | 42 |
| 1989 | 0.2 | 47 |
| 1988 | 0.3 | 42 |