| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2012 | 16.1 | 58 |
| 2011 | 18.2 | 60 |
| 2010 | 11.4 | 63 |
| 2009 | 4.1 | 71 |
| 2007 | 8.1 | 73 |
| 2006 | 9 | 74 |
| 2005 | 3.3 | 75 |
| 2004 | 1.4 | 79 |
| 2003 | 13.4 | 49 |
| 2002 | 24.9 | 46 |
| 2001 | 15.3 | 47 |
| 2000 | 2.8 | 62 |
| 1999 | 2.3 | 66 |
| 1998 | 1.9 | 66 |
| 1997 | 5.4 | 56 |
| 1996 | 2.6 | 59 |
| 1995 | 1.5 | 62 |
| 1994 | 1.8 | 57 |
| 1993 | 0.5 | 54 |
| 1992 | 0.2 | 55 |
| 1991 | 0.8 | 50 |
| 1990 | 0.5 | 44 |
| 1989 | 0.4 | 44 |
| 1988 | 0.4 | 41 |