| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 90 | 32 |
| 2014 | 49.8 | 46 |
| 2013 | 159.4 | 22 |
| 2012 | 129 | 28 |
| 2011 | 24.7 | 65 |
| 2010 | 147.5 | 25 |
| 2009 | 64.1 | 39 |
| 2008 | 85.6 | 42 |
| 2007 | 86.3 | 44 |
| 2006 | 89.2 | 36 |
| 2005 | 82.2 | 33 |
| 2004 | 58.6 | 27 |
| 2003 | 52.3 | 26 |
| 2002 | 33.4 | 31 |
| 2001 | 50.7 | 26 |
| 2000 | 33.7 | 34 |
| 1999 | 61 | 26 |
| 1998 | 73.1 | 16 |
| 1997 | 38.9 | 24 |
| 1996 | 23.4 | 31 |
| 1995 | 20.7 | 28 |
| 1994 | 13.7 | 31 |
| 1993 | 18 | 18 |
| 1992 | 21.1 | 15 |
| 1991 | 20.1 | 18 |
| 1990 | 24.4 | 15 |
| 1989 | 17.8 | 16 |
| 1988 | 11.1 | 17 |
| 1987 | 3.5 | 27 |
| 1986 | 2.6 | 26 |