| 时间 |
值 （亿美元） |
世界排名 |
| 2016 |
0.1 |
134 |
| 2015 |
0.1 |
143 |
| 2014 |
0.1 |
147 |
| 2013 |
0.2 |
146 |
| 2012 |
0.2 |
146 |
| 2011 |
0.1 |
142 |
| 2010 |
0.1 |
145 |
| 2009 |
0.1 |
147 |
| 2008 |
0 |
151 |
| 2007 |
0 |
146 |
| 2006 |
0 |
147 |
| 2005 |
0.1 |
151 |
| 2004 |
0 |
151 |
| 1994 |
0.4 |
105 |
| 1993 |
0.3 |
119 |
| 1992 |
0.2 |
116 |
| 1991 |
0.3 |
106 |
| 1988 |
0.3 |
100 |
| 1987 |
0.2 |
100 |
| 1986 |
0.2 |
92 |