| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 16 | 66 |
| 2015 | 15 | 102 |
| 2014 | 16 | 104 |
| 2013 | 15 | 106 |
| 2012 | 14 | 104 |
| 2011 | 13 | 106 |
| 2010 | 10 | 108 |
| 2009 | 8 | 114 |
| 2008 | 8 | 115 |
| 2007 | 8 | 113 |
| 2006 | 6 | 110 |
| 2005 | 4 | 114 |
| 2004 | 3 | 115 |
| 2003 | 2 | 117 |
| 2002 | 2 | 118 |
| 2001 | 2 | 113 |
| 2000 | 1 | 121 |
| 1999 | 1 | 122 |
| 1998 | 1 | 117 |
| 1997 | 1 | 120 |
| 1996 | 1 | 123 |
| 1995 | 0 | 133 |
| 1994 | 0 | 138 |
| 1993 | 0 | 132 |