| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2012 | 346.9 | 35 |
| 2011 | 328.5 | 36 |
| 2010 | 267.8 | 40 |
| 2009 | 172 | 48 |
| 2008 | 172.1 | 49 |
| 2007 | 292.5 | 46 |
| 2006 | 112.4 | 50 |
| 2005 | 69.5 | 50 |
| 2004 | 36.6 | 49 |
| 2003 | 26.3 | 47 |
| 2002 | 31 | 44 |
| 2001 | 31.5 | 46 |
| 2000 | 82 | 42 |
| 1999 | 198.4 | 33 |
| 1998 | 101.2 | 39 |
| 1997 | 203.9 | 33 |
| 1996 | 255.2 | 28 |
| 1995 | 147.3 | 29 |
| 1994 | 149.3 | 27 |
| 1993 | 67.5 | 32 |
| 1992 | 30.1 | 35 |
| 1991 | 14.9 | 38 |
| 1990 | 12.2 | 33 |
| 1989 | 24.1 | 28 |
| 1988 | 8.8 | 29 |