| 时间 |
值 （亿美元） |
世界排名 |
| 2012 |
1.4 |
79 |
| 2011 |
1.1 |
83 |
| 2010 |
1 |
85 |
| 2009 |
7.7 |
66 |
| 2008 |
1.6 |
83 |
| 2007 |
2.9 |
81 |
| 2006 |
2.9 |
79 |
| 2005 |
1.4 |
80 |
| 2004 |
1 |
81 |
| 2003 |
0.4 |
86 |
| 2002 |
0.2 |
90 |
| 2001 |
0.1 |
94 |
| 2000 |
0.1 |
94 |
| 1999 |
0.2 |
93 |
| 1998 |
1.4 |
70 |
| 1997 |
1.8 |
67 |
| 1996 |
1.2 |
62 |
| 1995 |
2.3 |
57 |
| 1994 |
0.7 |
64 |
| 1993 |
0.4 |
56 |