| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 3.4 | 124 |
| 2014 | 23.6 | 63 |
| 2013 | 37.2 | 47 |
| 2012 | 35.7 | 53 |
| 2011 | 17.6 | 73 |
| 2010 | 36.3 | 52 |
| 2009 | -4.1 | 193 |
| 2008 | 39.8 | 58 |
| 2007 | 53.6 | 53 |
| 2006 | 29.2 | 60 |
| 2005 | 17.8 | 64 |
| 2004 | 7.7 | 75 |
| 2003 | 5.1 | 78 |
| 2002 | 3.9 | 76 |
| 2001 | 1.6 | 95 |
| 2000 | 0 | 172 |
| 1999 | 0.1 | 149 |
| 1998 | -.2 | 180 |
| 1997 | 0 | 164 |
| 1996 | 0.1 | 152 |
| 1995 | 0 | 153 |
| 1994 | 0 | 139 |
| 1993 | 0 | 163 |
| 1992 | -.2 | 162 |
| 1991 | 0.1 | 105 |
| 1990 | 0 | 128 |
| 1989 | 0 | 130 |
| 1988 | 0 | 124 |
| 1987 | 0 | 128 |
| 1986 | 0 | 117 |