| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 52.1 | 68 |
| 2015 | 53.3 | 79 |
| 2014 | 53.4 | 79 |
| 2013 | 50.4 | 82 |
| 2012 | 47.7 | 84 |
| 2011 | 45.1 | 85 |
| 2010 | 43.3 | 88 |
| 2009 | 40.2 | 84 |
| 2008 | 35.1 | 86 |
| 2007 | 31.6 | 87 |
| 2006 | 29.1 | 87 |
| 2005 | 27.6 | 86 |
| 2004 | 27.1 | 85 |
| 2003 | 29.1 | 82 |
| 2002 | 29.5 | 81 |
| 2001 | 29.5 | 81 |
| 2000 | 28 | 81 |
| 1999 | 26 | 76 |
| 1998 | 24.1 | 77 |
| 1997 | 22 | 78 |
| 1996 | 20.7 | 79 |
| 1995 | 20.7 | 78 |
| 1994 | 20.4 | 72 |
| 1993 | 19.9 | 73 |
| 1992 | 18.3 | 71 |
| 1991 | 16.4 | 73 |
| 1990 | 16.6 | 71 |
| 1989 | 16.6 | 61 |
| 1988 | 16 | 61 |
| 1987 | 15.2 | 62 |
| 1986 | 14.2 | 61 |