| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 53.7 | 31 |
| 2015 | 43.2 | 46 |
| 2014 | 38.7 | 53 |
| 2013 | 38.5 | 44 |
| 2012 | 30.5 | 63 |
| 2011 | 23.7 | 66 |
| 2010 | 32.1 | 54 |
| 2009 | 46.4 | 45 |
| 2008 | 136.7 | 29 |
| 2007 | 101 | 39 |
| 2006 | 110.1 | 32 |
| 2005 | 65 | 38 |
| 2004 | 64.4 | 25 |
| 2003 | 18.4 | 44 |
| 2002 | 11.4 | 49 |
| 2001 | 11.6 | 46 |
| 2000 | 10.4 | 45 |
| 1999 | 10.4 | 48 |
| 1998 | 20.3 | 39 |
| 1997 | 12.2 | 47 |
| 1996 | 2.6 | 69 |
| 1995 | 4.2 | 51 |
| 1994 | 3.4 | 55 |
| 1993 | 0.9 | 77 |
| 1992 | 0.8 | 73 |
| 1991 | 0.4 | 77 |
| 1990 | 0 | 137 |