| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 39 | 39 |
| 2015 | 33.4 | 46 |
| 2014 | 31 | 51 |
| 2013 | 33.8 | 50 |
| 2012 | 29 | 52 |
| 2011 | 27 | 50 |
| 2010 | 24.4 | 52 |
| 2009 | 21.2 | 54 |
| 2008 | 22.7 | 54 |
| 2007 | 20.1 | 52 |
| 2006 | 16.1 | 53 |
| 2005 | 13.7 | 54 |
| 2004 | 12.4 | 54 |
| 2003 | 13 | 50 |
| 2002 | 12 | 46 |
| 2001 | 11.2 | 47 |
| 2000 | 13 | 45 |
| 1999 | 13.4 | 45 |
| 1998 | 12.3 | 49 |
| 1997 | 15.8 | 47 |
| 1996 | 18.8 | 44 |
| 1995 | 17 | 44 |
| 1994 | 13.9 | 43 |
| 1993 | 11.7 | 45 |
| 1992 | 10.8 | 44 |
| 1991 | 9.1 | 46 |
| 1990 | 9.5 | 47 |
| 1989 | 9.5 | 46 |
| 1988 | 9.3 | 46 |
| 1987 | 6.5 | 50 |
| 1986 | 5.9 | 47 |