| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 4.1 | 120 |
| 2014 | 6.7 | 104 |
| 2013 | -11.3 | 190 |
| 2012 | -18.9 | 195 |
| 2011 | 0.5 | 167 |
| 2010 | 5.5 | 103 |
| 2009 | 7.1 | 94 |
| 2008 | 28 | 63 |
| 2007 | 8.3 | 100 |
| 2006 | 8.8 | 83 |
| 2005 | 9.4 | 78 |
| 2004 | 10 | 64 |
| 2003 | 8.1 | 64 |
| 2002 | 10.1 | 53 |
| 2001 | 8.3 | 53 |
| 2000 | 6.8 | 60 |
| 1999 | 6.4 | 57 |
| 1998 | 7.3 | 57 |
| 1997 | 10 | 49 |
| 1996 | 3.6 | 58 |
| 1995 | 3 | 57 |
| 1994 | 5.2 | 47 |
| 1993 | 3.8 | 51 |
| 1992 | 1.8 | 50 |
| 1991 | 1.7 | 48 |
| 1990 | 1.1 | 57 |
| 1989 | 1.5 | 46 |
| 1988 | 0.6 | 55 |
| 1987 | 0.3 | 68 |
| 1986 | -.1 | 131 |