| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 5 | 116 |
| 2014 | 5 | 114 |
| 2013 | 11.3 | 80 |
| 2012 | 13.9 | 87 |
| 2011 | 5.9 | 119 |
| 2010 | 1.3 | 146 |
| 2009 | 0 | 183 |
| 2008 | 3.4 | 130 |
| 2007 | 1.4 | 148 |
| 2006 | 1.5 | 137 |
| 2005 | 8.1 | 82 |
| 2004 | 4 | 90 |
| 2003 | 1 | 122 |
| 2002 | 0.7 | 123 |
| 2001 | 0.8 | 117 |
| 2000 | 0.4 | 130 |
| 1999 | 0.2 | 144 |
| 1998 | 0 | 170 |
| 1997 | 0 | 178 |
| 1996 | 0 | 172 |
| 1995 | 0.1 | 144 |
| 1994 | 0 | 147 |
| 1993 | 0.2 | 115 |
| 1992 | 0.1 | 118 |
| 1991 | 0 | 123 |
| 1990 | 0.1 | 110 |
| 1989 | 0 | 110 |
| 1988 | 0 | 110 |
| 1987 | 0 | 113 |
| 1986 | 0 | 93 |