| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 37.7 | 40 |
| 2015 | 35.6 | 43 |
| 2014 | 41.1 | 43 |
| 2013 | 47.2 | 41 |
| 2012 | 41.4 | 45 |
| 2011 | 49 | 37 |
| 2010 | 47.2 | 34 |
| 2009 | 49.5 | 30 |
| 2008 | 48.1 | 31 |
| 2007 | 43.7 | 30 |
| 2006 | 40.7 | 30 |
| 2005 | 40.4 | 29 |
| 2004 | 37.2 | 29 |
| 2003 | 31.1 | 33 |
| 2002 | 26 | 34 |
| 2001 | 23.2 | 36 |
| 2000 | 22 | 35 |
| 1999 | 24.1 | 34 |
| 1998 | 23.4 | 34 |
| 1997 | 23.9 | 37 |
| 1996 | 26 | 34 |
| 1995 | 26.7 | 32 |
| 1994 | 21.7 | 35 |
| 1993 | 21.9 | 32 |
| 1992 | 25.3 | 30 |
| 1991 | 21.2 | 30 |
| 1990 | 18.7 | 33 |
| 1989 | 14.6 | 36 |
| 1988 | 13.5 | 37 |
| 1987 | 11.3 | 41 |
| 1986 | 9.4 | 39 |