| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 0.5 | 166 |
| 2014 | 0.8 | 155 |
| 2013 | 1.2 | 146 |
| 2012 | 0 | 189 |
| 2011 | 0 | 181 |
| 2010 | 0 | 185 |
| 2009 | 0 | 182 |
| 2008 | 0 | 185 |
| 2007 | 0 | 190 |
| 2006 | 0 | 185 |
| 2005 | 0 | 180 |
| 2004 | 0 | 179 |
| 2001 | 0 | 172 |
| 2000 | 0.1 | 152 |
| 1999 | 0 | 171 |
| 1998 | 0 | 167 |
| 1997 | 0 | 172 |
| 1996 | 0 | 170 |
| 1995 | 0 | 155 |
| 1994 | 0 | 158 |
| 1993 | 0 | 152 |
| 1992 | 0 | 140 |
| 1991 | 0 | 131 |
| 1990 | 0 | 124 |
| 1989 | 0 | 120 |
| 1988 | 0 | 115 |
| 1987 | 0 | 116 |
| 1986 | 0 | 103 |