| 时间 |
值 （亿美元） |
世界排名 |
| 2015 |
26.9 |
52 |
| 2014 |
28.5 |
53 |
| 2013 |
27.1 |
55 |
| 2012 |
28.8 |
53 |
| 2011 |
21.3 |
57 |
| 2010 |
21.4 |
53 |
| 2009 |
21 |
55 |
| 2008 |
20.2 |
56 |
| 2007 |
18.9 |
54 |
| 2006 |
17.1 |
51 |
| 2005 |
16.5 |
50 |
| 2004 |
13 |
53 |
| 2003 |
12.6 |
51 |
| 1993 |
4.1 |
60 |
| 1991 |
15.8 |
37 |
| 1990 |
18.4 |
34 |
| 1989 |
17.6 |
32 |
| 1988 |
17.8 |
28 |
| 1987 |
16.5 |
29 |
| 1986 |
15.7 |
31 |