| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 7.7 | 50 |
| 2015 | 10.7 | 92 |
| 2014 | 10.4 | 89 |
| 2013 | -8.4 | 188 |
| 2012 | 4 | 128 |
| 2011 | 9.4 | 100 |
| 2010 | 46.7 | 47 |
| 2009 | 81.2 | 33 |
| 2008 | 37.8 | 59 |
| 2007 | 47 | 55 |
| 2006 | 35 | 54 |
| 2005 | 25 | 57 |
| 2004 | 12 | 59 |
| 2003 | 6.2 | 71 |
| 2002 | 6.2 | 68 |
| 2001 | 3 | 80 |
| 2000 | 2.5 | 79 |
| 1999 | 1.1 | 103 |
| 1998 | 3.5 | 73 |
| 1997 | 4.2 | 64 |
| 1996 | 3.4 | 61 |
| 1995 | 0.9 | 90 |
| 1994 | 1.3 | 70 |
| 1993 | 0.7 | 84 |
| 1992 | 0.4 | 81 |
| 1991 | 0.4 | 74 |
| 1990 | 0 | 118 |
| 1989 | 0 | 132 |
| 1988 | -.2 | 139 |
| 1987 | 0 | 132 |
| 1986 | 0 | 121 |