| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 30 | 83 |
| 2015 | 30 | 97 |
| 2014 | 28.3 | 101 |
| 2013 | 27.3 | 103 |
| 2012 | 27.7 | 100 |
| 2011 | 26.9 | 100 |
| 2010 | 25 | 105 |
| 2009 | 23.7 | 99 |
| 2008 | 21.9 | 101 |
| 2007 | 20.4 | 100 |
| 2006 | 20.1 | 99 |
| 2005 | 19 | 95 |
| 2004 | 17.1 | 96 |
| 2003 | 12.7 | 103 |
| 2002 | 12.8 | 102 |
| 2001 | 15.1 | 96 |
| 2000 | 14.9 | 95 |
| 1999 | 13.9 | 93 |
| 1998 | 12.7 | 95 |
| 1997 | 11.4 | 96 |
| 1996 | 10.1 | 100 |
| 1995 | 8.4 | 100 |
| 1994 | 7.5 | 98 |