| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 42.6 | 47 |
| 2014 | 41.7 | 51 |
| 2013 | 37.3 | 46 |
| 2012 | 31.3 | 62 |
| 2011 | 33.9 | 57 |
| 2010 | 36.3 | 51 |
| 2009 | 45.5 | 46 |
| 2008 | 12.8 | 95 |
| 2007 | 8.6 | 99 |
| 2006 | 7.3 | 87 |
| 2005 | 4.2 | 101 |
| 2004 | 3.5 | 95 |
| 2003 | 2.3 | 97 |
| 2002 | 2.8 | 84 |
| 2001 | 1.7 | 94 |
| 2000 | 1.3 | 100 |
| 1999 | 1.3 | 100 |
| 1998 | 0.6 | 124 |
| 1997 | 1.1 | 101 |
| 1996 | 1.1 | 92 |
| 1995 | 2.3 | 64 |
| 1994 | 1 | 78 |
| 1993 | 0.8 | 81 |