| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 34.2 | 42 |
| 2015 | 36.2 | 42 |
| 2014 | 40.3 | 46 |
| 2013 | 43.9 | 44 |
| 2012 | 41.4 | 46 |
| 2011 | 36.8 | 45 |
| 2010 | 37.3 | 43 |
| 2009 | 34.5 | 43 |
| 2008 | 48.1 | 32 |
| 2007 | 41 | 34 |
| 2006 | 29.9 | 40 |
| 2005 | 24.1 | 43 |
| 2004 | 16.9 | 46 |
| 2003 | 14.3 | 46 |
| 2002 | 11.8 | 47 |
| 2001 | 10.9 | 49 |
| 2000 | 11.4 | 47 |
| 1999 | 9.4 | 55 |
| 1998 | 14.1 | 47 |
| 1997 | 20.7 | 42 |
| 1996 | 14.6 | 45 |
| 1995 | 13.6 | 47 |
| 1994 | 13.1 | 46 |
| 1993 | 3.1 | 65 |