| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 0.5 | 165 |
| 2014 | 0.3 | 171 |
| 2013 | 0.7 | 155 |
| 2012 | 0.9 | 160 |
| 2011 | 0.9 | 158 |
| 2010 | 0.9 | 160 |
| 2009 | 0.4 | 165 |
| 2008 | 0 | 188 |
| 2007 | 0.1 | 187 |
| 2006 | -.1 | 187 |
| 2005 | 0 | 177 |
| 2004 | 0 | 184 |
| 2003 | 0.1 | 159 |
| 2002 | -.1 | 185 |
| 2001 | 0.2 | 139 |
| 2000 | 0 | 171 |
| 1999 | 0 | 156 |
| 1998 | 0.1 | 150 |
| 1997 | 0.2 | 138 |
| 1996 | 0.2 | 129 |
| 1991 | 0 | 124 |
| 1990 | 0.1 | 113 |
| 1989 | 0 | 122 |
| 1988 | 0 | 119 |
| 1987 | 0 | 115 |
| 1986 | 0 | 105 |