| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 41.7 | 37 |
| 2015 | 45.3 | 38 |
| 2014 | 49.2 | 39 |
| 2013 | 49.2 | 40 |
| 2012 | 45.1 | 39 |
| 2011 | 46.9 | 38 |
| 2010 | 38.5 | 41 |
| 2009 | 39.6 | 39 |
| 2008 | 44.1 | 38 |
| 2007 | 39.7 | 36 |
| 2006 | 32.7 | 37 |
| 2005 | 31.2 | 36 |
| 2004 | 28.2 | 36 |
| 2003 | 28.8 | 34 |
| 2002 | 22.4 | 36 |
| 2001 | 19.3 | 38 |
| 2000 | 15.3 | 44 |
| 1999 | 16.6 | 42 |
| 1998 | 11.6 | 51 |
| 1997 | 20.9 | 41 |
| 1996 | 24.2 | 37 |
| 1995 | 24.4 | 36 |
| 1994 | 21.2 | 36 |
| 1993 | 19.2 | 36 |
| 1992 | 17.7 | 38 |
| 1991 | 15.7 | 38 |
| 1990 | 11.2 | 42 |
| 1989 | 10.2 | 42 |
| 1988 | 8.6 | 49 |
| 1987 | 13.3 | 36 |
| 1986 | 8.9 | 40 |