| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 2 | 137 |
| 2014 | -.3 | 188 |
| 2013 | 0.2 | 171 |
| 2012 | -.6 | 193 |
| 2011 | -3.1 | 188 |
| 2010 | 0.3 | 176 |
| 2009 | 4.2 | 110 |
| 2008 | -.3 | 192 |
| 2007 | 0.9 | 160 |
| 2006 | 0.1 | 177 |
| 2005 | 0.3 | 155 |
| 2004 | 0.3 | 154 |
| 2003 | 1.1 | 120 |
| 2002 | 0.2 | 148 |
| 2001 | 0.6 | 121 |
| 2000 | 1 | 111 |
| 1999 | 3 | 78 |
| 1998 | 1.1 | 109 |
| 1997 | 0.3 | 135 |
| 1996 | 1.1 | 89 |
| 1995 | 4.5 | 48 |
| 1994 | 0.6 | 94 |
| 1993 | 0.6 | 87 |
| 1992 | 1 | 63 |
| 1991 | 1.2 | 58 |
| 1990 | 1.6 | 48 |
| 1989 | 2 | 39 |
| 1988 | 1.5 | 42 |
| 1987 | 0.9 | 42 |
| 1986 | 0.9 | 42 |