| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 9.5 | 108 |
| 2015 | 8.6 | 132 |
| 2014 | 8.1 | 135 |
| 2013 | 7.6 | 139 |
| 2012 | 7.3 | 140 |
| 2011 | 7 | 140 |
| 2010 | 6.8 | 151 |
| 2009 | 6.3 | 139 |
| 2008 | 6.3 | 136 |
| 2007 | 5.7 | 135 |
| 2006 | 6.1 | 131 |
| 2005 | 6.1 | 125 |
| 2004 | 5.7 | 125 |
| 2003 | 5.6 | 125 |
| 2002 | 5.3 | 124 |
| 2001 | 5.5 | 120 |
| 2000 | 5.7 | 117 |
| 1999 | 5.4 | 115 |
| 1998 | 5 | 116 |
| 1997 | 4.8 | 114 |
| 1996 | 5 | 110 |
| 1995 | 4.9 | 108 |
| 1994 | 4.6 | 105 |
| 1993 | 3 | 106 |
| 1992 | 3.1 | 102 |
| 1991 | 3.5 | 99 |
| 1990 | 5.3 | 92 |
| 1989 | 4 | 82 |
| 1988 | 5 | 77 |
| 1987 | 8.3 | 71 |
| 1986 | 7.9 | 69 |