| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2013 | 53.1 | 37 |
| 2012 | 49.7 | 36 |
| 2011 | 23.8 | 55 |
| 2010 | 33.6 | 47 |
| 2009 | 40.2 | 38 |
| 2008 | 43.3 | 39 |
| 2007 | 29.7 | 45 |
| 2006 | 30 | 39 |
| 2005 | 20.5 | 45 |
| 2004 | 14.5 | 50 |
| 2003 | 9.9 | 54 |
| 2002 | 10.7 | 50 |
| 2001 | 19.1 | 39 |
| 2000 | 17.9 | 42 |
| 1999 | 14.1 | 44 |
| 1998 | 14.5 | 43 |
| 1997 | 15.4 | 48 |
| 1996 | 7.3 | 58 |
| 1995 | 12 | 49 |
| 1994 | 9.3 | 51 |
| 1993 | 12.9 | 42 |
| 1992 | 9.9 | 47 |
| 1991 | 9.8 | 44 |
| 1990 | 7.4 | 54 |
| 1989 | 12 | 40 |
| 1988 | 11 | 40 |
| 1987 | 7.7 | 48 |
| 1986 | 10 | 38 |