| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2012 | 27.9 | 54 |
| 2011 | 40.2 | 56 |
| 2010 | 94.5 | 52 |
| 2009 | 136.5 | 51 |
| 2008 | 280.1 | 46 |
| 2007 | 174.3 | 49 |
| 2006 | 200.5 | 46 |
| 2005 | 238.1 | 44 |
| 2004 | 53.3 | 47 |
| 2003 | 26.1 | 48 |
| 2002 | 13.4 | 49 |
| 2001 | 9.3 | 52 |
| 2000 | 4.2 | 58 |
| 1999 | 5.5 | 56 |
| 1998 | 6.5 | 57 |
| 1997 | 5 | 57 |
| 1996 | 3 | 57 |
| 1995 | 5.2 | 50 |
| 1994 | 6.3 | 49 |
| 1993 | 13.8 | 43 |
| 1992 | 13.2 | 40 |
| 1991 | 4.3 | 41 |
| 1990 | 4.1 | 36 |
| 1989 | 6.5 | 34 |
| 1988 | 3.4 | 32 |