| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 11.6 | 103 |
| 2015 | 11.6 | 123 |
| 2014 | 11.3 | 123 |
| 2013 | 11.6 | 126 |
| 2012 | 12.5 | 123 |
| 2011 | 12.5 | 121 |
| 2010 | 13.9 | 126 |
| 2009 | 14.8 | 116 |
| 2008 | 14.4 | 115 |
| 2007 | 13.8 | 114 |
| 2006 | 12.9 | 114 |
| 2005 | 11.8 | 110 |
| 2004 | 10.3 | 112 |
| 2003 | 13.4 | 101 |
| 2002 | 13.4 | 99 |
| 2001 | 10 | 107 |
| 2000 | 10.6 | 105 |
| 1999 | 10.5 | 99 |
| 1998 | 17.1 | 89 |
| 1997 | 21.1 | 79 |
| 1996 | 18 | 85 |
| 1995 | 19.7 | 80 |