| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 1.2 | 64 |
| 2015 | 2.3 | 135 |
| 2014 | 3.5 | 132 |
| 2013 | 2.9 | 131 |
| 2012 | 2.8 | 137 |
| 2011 | 3.5 | 131 |
| 2010 | 2.1 | 133 |
| 2009 | 1.4 | 134 |
| 2008 | 7.3 | 115 |
| 2007 | 5.4 | 116 |
| 2006 | 2.6 | 123 |
| 2005 | 1.9 | 121 |
| 2004 | 0.9 | 130 |
| 2003 | 0.7 | 131 |
| 2002 | 0.8 | 116 |
| 2001 | 0.5 | 127 |
| 2000 | 1.3 | 102 |
| 1999 | 0.4 | 136 |
| 1998 | 0.8 | 121 |
| 1997 | 0.8 | 114 |
| 1996 | 0.2 | 125 |
| 1995 | 0.3 | 120 |
| 1994 | 0.1 | 129 |
| 1993 | 0.1 | 122 |
| 1992 | 0.2 | 99 |