| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 2.5 | 98 |
| 2015 | 2.1 | 108 |
| 2014 | 2.4 | 109 |
| 2013 | 2.4 | 110 |
| 2012 | 2 | 111 |
| 2011 | 2.3 | 104 |
| 2010 | 2 | 106 |
| 2009 | 2.2 | 103 |
| 2008 | 2.2 | 104 |
| 2007 | 1.9 | 105 |
| 2006 | 1.5 | 104 |
| 2005 | 1.2 | 107 |
| 2004 | 1.1 | 108 |
| 2003 | 1 | 105 |
| 2002 | 0.7 | 103 |
| 2001 | 0.7 | 103 |
| 2000 | 0.6 | 103 |
| 1999 | 0.8 | 99 |
| 1998 | 0.8 | 100 |
| 1997 | 0.7 | 104 |
| 1996 | 0.8 | 96 |
| 1995 | 0.8 | 94 |
| 1994 | 0.7 | 95 |
| 1993 | 1.2 | 84 |
| 1992 | 1.1 | 83 |
| 1991 | 1.1 | 80 |
| 1990 | 1.2 | 83 |
| 1989 | 1 | 80 |
| 1988 | 1.1 | 78 |
| 1987 | 1 | 76 |
| 1986 | 0.9 | 71 |