| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 9.3 | 64 |
| 2015 | 8.4 | 72 |
| 2014 | 8.2 | 77 |
| 2013 | 8.6 | 77 |
| 2012 | 8.4 | 75 |
| 2011 | 6.5 | 79 |
| 2010 | 6.2 | 79 |
| 2009 | 5.8 | 80 |
| 2008 | 5.8 | 82 |
| 2007 | 4.9 | 80 |
| 2006 | 3.8 | 83 |
| 2005 | 3.2 | 82 |
| 2004 | 2.6 | 84 |
| 2003 | 2.5 | 81 |
| 2002 | 2.1 | 83 |
| 2001 | 2 | 83 |
| 2000 | 1.7 | 84 |
| 1999 | 1.5 | 85 |
| 1998 | 1.7 | 82 |
| 1997 | 1.8 | 81 |
| 1996 | 1.7 | 78 |
| 1995 | 1.5 | 78 |
| 1994 | 1.2 | 84 |
| 1993 | 1.1 | 89 |
| 1992 | 1.6 | 75 |
| 1991 | 1.9 | 72 |
| 1990 | 2.5 | 66 |
| 1989 | 2.3 | 63 |
| 1988 | 2.5 | 60 |
| 1987 | 2.5 | 59 |
| 1986 | 1.8 | 57 |