| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 10.5 | 128 |
| 2014 | 10.6 | 125 |
| 2013 | 10.2 | 128 |
| 2012 | 10 | 129 |
| 2011 | 9 | 130 |
| 2010 | 8.6 | 143 |
| 2009 | 7.9 | 135 |
| 2008 | 8.2 | 129 |
| 2007 | 8.9 | 125 |
| 2006 | 7.9 | 122 |
| 2005 | 7 | 122 |
| 2004 | 7.1 | 120 |
| 2003 | 7.2 | 119 |
| 2002 | 5.9 | 122 |
| 2001 | 4.3 | 124 |
| 2000 | 4.3 | 123 |
| 1999 | 3.9 | 118 |
| 1998 | 3.4 | 119 |
| 1997 | 2.9 | 120 |
| 1996 | 2.9 | 117 |
| 1995 | 2.7 | 116 |
| 1994 | 2.8 | 110 |
| 1993 | 2.8 | 107 |
| 1992 | 2.7 | 103 |
| 1991 | 3.6 | 98 |
| 1990 | 4.9 | 94 |
| 1989 | 5 | 79 |
| 1988 | 4.8 | 78 |
| 1987 | 4.6 | 79 |
| 1986 | 4.2 | 77 |