| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 6.3 | 111 |
| 2015 | 6.9 | 135 |
| 2014 | 6 | 140 |
| 2013 | 6.3 | 144 |
| 2012 | 4.9 | 146 |
| 2011 | 3.3 | 147 |
| 2010 | 2.9 | 162 |
| 2009 | 3.4 | 146 |
| 2008 | 3.2 | 144 |
| 2007 | 3.2 | 142 |
| 2006 | 3.8 | 136 |
| 2005 | 3.8 | 131 |
| 2004 | 3.1 | 131 |
| 2003 | 2.7 | 132 |
| 2002 | 2.3 | 131 |
| 2001 | 2.7 | 129 |
| 2000 | 2.7 | 127 |
| 1999 | 2.7 | 122 |
| 1998 | 2.9 | 121 |
| 1997 | 2.1 | 122 |
| 1996 | 2.2 | 119 |
| 1995 | 2.3 | 117 |
| 1994 | 2.3 | 111 |
| 1993 | 2.5 | 108 |
| 1992 | 2.3 | 104 |
| 1991 | 2.8 | 101 |
| 1990 | 2.8 | 99 |
| 1989 | 2.7 | 86 |
| 1988 | 2.4 | 84 |
| 1987 | 2.9 | 83 |
| 1986 | 2.9 | 82 |