| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 44.8 | 73 |
| 2015 | 44.3 | 82 |
| 2014 | 42.9 | 83 |
| 2013 | 41.8 | 87 |
| 2012 | 41 | 88 |
| 2011 | 39.7 | 87 |
| 2010 | 39.2 | 89 |
| 2009 | 39.4 | 85 |
| 2008 | 40.7 | 84 |
| 2007 | 38.9 | 83 |
| 2006 | 36.5 | 83 |
| 2005 | 34.6 | 82 |
| 2004 | 33.6 | 82 |
| 2003 | 32.6 | 80 |
| 2002 | 31.3 | 80 |
| 2001 | 30.4 | 80 |
| 2000 | 29.4 | 79 |
| 1999 | 30.5 | 74 |
| 1998 | 30.4 | 72 |
| 1997 | 29.8 | 72 |
| 1996 | 30.2 | 71 |
| 1995 | 31.9 | 68 |
| 1994 | 28.1 | 66 |
| 1993 | 27 | 66 |