| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 3.2 | 126 |
| 2014 | 3.2 | 137 |
| 2013 | 7.3 | 97 |
| 2012 | 9.9 | 97 |
| 2011 | 19.8 | 72 |
| 2010 | 27.3 | 56 |
| 2009 | 16.4 | 69 |
| 2008 | -7.9 | 195 |
| 2007 | 12.4 | 91 |
| 2006 | 4.7 | 103 |
| 2005 | 7.7 | 85 |
| 2004 | 3.4 | 98 |
| 2003 | 6.9 | 68 |
| 2002 | 3.2 | 80 |
| 2001 | 9.4 | 52 |
| 2000 | 1.5 | 92 |
| 1999 | 1.5 | 96 |
| 1998 | 2.7 | 79 |
| 1997 | 0.5 | 122 |
| 1996 | 3.8 | 57 |
| 1995 | 1.3 | 75 |
| 1994 | 0.2 | 121 |
| 1993 | 0.2 | 108 |
| 1992 | 0.1 | 123 |
| 1991 | 0.4 | 76 |
| 1990 | 0.1 | 102 |
| 1989 | 0 | 118 |
| 1988 | 0 | 122 |
| 1987 | 0 | 112 |
| 1986 | 0.1 | 86 |