| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 22.5 | 41 |
| 2015 | 15.2 | 79 |
| 2014 | 57.9 | 39 |
| 2013 | 82.3 | 36 |
| 2012 | 46.3 | 49 |
| 2011 | 41.4 | 53 |
| 2010 | 36.9 | 49 |
| 2009 | 76.2 | 35 |
| 2008 | 98.9 | 36 |
| 2007 | 65.9 | 47 |
| 2006 | 6.2 | 95 |
| 2005 | 65.2 | 37 |
| 2004 | 7 | 77 |
| 2003 | 7.8 | 65 |
| 2002 | 14.8 | 46 |
| 2001 | 72.7 | 19 |
| 2000 | 9.7 | 50 |
| 1999 | 15 | 40 |
| 1998 | 5.5 | 65 |
| 1997 | 38.1 | 26 |
| 1996 | 8.2 | 45 |
| 1995 | 12.5 | 36 |
| 1994 | 3.7 | 53 |
| 1993 | 0.1 | 126 |
| 1992 | 0 | 127 |
| 1991 | 2.5 | 43 |
| 1990 | -.8 | 145 |
| 1989 | -2 | 144 |
| 1988 | 1.6 | 40 |
| 1987 | -1.9 | 142 |
| 1986 | -.5 | 136 |