| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 9.8 | 97 |
| 2014 | 18.7 | 72 |
| 2013 | 13.3 | 78 |
| 2012 | 8.6 | 102 |
| 2011 | 13.3 | 85 |
| 2010 | 20.2 | 64 |
| 2009 | 23.4 | 61 |
| 2008 | 54.4 | 50 |
| 2007 | 55.9 | 51 |
| 2006 | 42.7 | 51 |
| 2005 | 22 | 59 |
| 2004 | 11.2 | 61 |
| 2003 | 5.3 | 76 |
| 2002 | 8.3 | 58 |
| 2001 | 3.8 | 76 |
| 2000 | 3.1 | 70 |
| 1999 | 5.3 | 61 |
| 1998 | 5.1 | 67 |
| 1997 | 7.2 | 56 |
| 1996 | 9.2 | 44 |
| 1995 | 7.2 | 44 |
| 1994 | 4.2 | 51 |
| 1993 | 3.5 | 53 |
| 1992 | 3.4 | 42 |
| 1991 | 2.6 | 42 |
| 1990 | 2.5 | 39 |
| 1989 | 2.1 | 38 |
| 1988 | 1.9 | 39 |
| 1987 | 1.3 | 35 |
| 1986 | 1.1 | 41 |