| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 6.2 | 108 |
| 2014 | 10.1 | 92 |
| 2013 | 7.7 | 96 |
| 2012 | 8.3 | 104 |
| 2011 | 7 | 112 |
| 2010 | 5 | 108 |
| 2009 | 5.7 | 102 |
| 2008 | 7.7 | 110 |
| 2007 | 2.7 | 133 |
| 2006 | 2.7 | 122 |
| 2005 | 3.3 | 107 |
| 2004 | 3.1 | 100 |
| 2003 | 1 | 123 |
| 2002 | 0 | 175 |
| 2001 | -1 | 183 |
| 2000 | 2.8 | 73 |
| 1999 | -1.6 | 181 |
| 1998 | 1.5 | 106 |
| 1997 | -3.1 | 184 |
| 1996 | -4.9 | 181 |
| 1995 | -3.1 | 177 |
| 1994 | -1 | 174 |
| 1993 | -1.1 | 172 |
| 1992 | 1.3 | 56 |
| 1991 | -.5 | 153 |
| 1990 | 0.7 | 63 |
| 1989 | -.3 | 141 |
| 1988 | 1.3 | 43 |
| 1987 | 0.9 | 44 |
| 1986 | 1.1 | 39 |