| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 31.6 | 79 |
| 2015 | 18.6 | 113 |
| 2014 | 19.9 | 111 |
| 2013 | 17 | 117 |
| 2012 | 19.3 | 115 |
| 2011 | 12.9 | 120 |
| 2010 | 12.5 | 129 |
| 2009 | 11.7 | 120 |
| 2008 | 14 | 117 |
| 2007 | 16 | 108 |
| 2006 | 13.5 | 110 |
| 2005 | 10.5 | 112 |
| 2004 | 9.5 | 114 |
| 2003 | 9.4 | 113 |
| 2002 | 10.5 | 109 |
| 2001 | 4 | 126 |
| 2000 | 3.8 | 124 |
| 1999 | 3.3 | 120 |
| 1998 | 8.1 | 107 |
| 1997 | 4.9 | 112 |
| 1996 | 1 | 126 |
| 1995 | 3.4 | 115 |
| 1994 | 4.9 | 103 |
| 1993 | 6.6 | 97 |
| 1992 | 6.6 | 92 |
| 1991 | 7.2 | 90 |
| 1990 | 5.2 | 93 |
| 1989 | 4.9 | 80 |
| 1988 | 4.7 | 79 |
| 1987 | 4.9 | 78 |
| 1986 | 5.6 | 74 |