| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 3.9 | 85 |
| 2015 | 3.5 | 95 |
| 2014 | 4 | 93 |
| 2013 | 3.9 | 89 |
| 2012 | 3.5 | 92 |
| 2011 | 3.5 | 92 |
| 2010 | 3.5 | 89 |
| 2009 | 3.4 | 93 |
| 2008 | 3.5 | 92 |
| 2007 | 3 | 92 |
| 2006 | 2.6 | 92 |
| 2005 | 2.2 | 92 |
| 2004 | 2.2 | 90 |
| 2003 | 1.9 | 91 |
| 2002 | 1.5 | 93 |
| 2001 | 1.2 | 93 |
| 2000 | 1.2 | 92 |
| 1999 | 1.5 | 86 |
| 1998 | 1.3 | 90 |
| 1997 | 1.3 | 88 |
| 1996 | 1.2 | 87 |
| 1995 | 1.1 | 88 |
| 1994 | 1.2 | 83 |
| 1993 | 1.8 | 79 |
| 1992 | 1.7 | 71 |
| 1991 | 1.9 | 73 |
| 1990 | 1.6 | 74 |
| 1989 | 1.5 | 71 |
| 1988 | 1.6 | 71 |
| 1987 | 1.5 | 67 |
| 1986 | 1.3 | 63 |