| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2012 | 250 | 38 |
| 2011 | 213.7 | 42 |
| 2010 | 179.4 | 44 |
| 2009 | 180.1 | 47 |
| 2008 | 316.1 | 44 |
| 2007 | 216.5 | 48 |
| 2006 | 197.6 | 47 |
| 2005 | 174.3 | 46 |
| 2004 | 154 | 40 |
| 2003 | 104.8 | 38 |
| 2002 | 74.7 | 37 |
| 2001 | 84.3 | 37 |
| 2000 | 107.8 | 39 |
| 1999 | 112.5 | 38 |
| 1998 | 103.1 | 38 |
| 1997 | 107.9 | 39 |
| 1996 | 88.8 | 33 |
| 1995 | 84.1 | 34 |
| 1994 | 71.6 | 33 |
| 1993 | 67.8 | 31 |
| 1992 | 31.7 | 34 |
| 1991 | 28.9 | 32 |
| 1990 | 19.3 | 31 |
| 1989 | 30.3 | 27 |
| 1988 | 11.2 | 28 |