| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 4.1 | 81 |
| 2015 | 2.8 | 101 |
| 2014 | 3 | 102 |
| 2013 | 2.8 | 103 |
| 2012 | 2.6 | 102 |
| 2011 | 2.9 | 97 |
| 2010 | 2.6 | 100 |
| 2009 | 3.6 | 89 |
| 2008 | 5.8 | 81 |
| 2007 | 4.8 | 82 |
| 2006 | 3.7 | 84 |
| 2005 | 2.7 | 87 |
| 2004 | 2.3 | 88 |
| 2003 | 1.9 | 90 |
| 2002 | 1.5 | 91 |
| 2001 | 0.9 | 101 |
| 2000 | 0.7 | 100 |
| 1999 | 0.6 | 105 |
| 1998 | 0.4 | 112 |
| 1997 | 0.4 | 121 |
| 1996 | 0.4 | 115 |
| 1995 | 0.5 | 104 |