| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 52.1 | 32 |
| 2015 | 50.6 | 34 |
| 2014 | 46.2 | 40 |
| 2013 | 46.2 | 43 |
| 2012 | 42.9 | 42 |
| 2011 | 40.5 | 43 |
| 2010 | 34.5 | 45 |
| 2009 | 29.5 | 50 |
| 2008 | 27.6 | 52 |
| 2007 | 22.8 | 50 |
| 2006 | 18.3 | 50 |
| 2005 | 16.8 | 49 |
| 2004 | 14.5 | 49 |
| 2003 | 13.5 | 49 |
| 2002 | 10.7 | 51 |
| 2001 | 31.8 | 26 |
| 2000 | 32.7 | 24 |
| 1999 | 34.6 | 24 |
| 1998 | 34 | 26 |
| 1997 | 33.4 | 25 |
| 1996 | 33.8 | 28 |
| 1995 | 38 | 24 |
| 1994 | 37.5 | 22 |
| 1993 | 33.7 | 23 |
| 1992 | 32.5 | 27 |
| 1991 | 28.6 | 26 |
| 1990 | 20.5 | 30 |
| 1989 | 14.4 | 37 |
| 1988 | 26.8 | 24 |
| 1987 | 25.4 | 24 |
| 1986 | 25.7 | 21 |