| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 25.8 | 87 |
| 2015 | 26.2 | 102 |
| 2014 | 27.5 | 102 |
| 2013 | 31.2 | 98 |
| 2012 | 24.8 | 105 |
| 2011 | 23.4 | 105 |
| 2010 | 19 | 116 |
| 2009 | 16.9 | 110 |
| 2008 | 14.7 | 114 |
| 2007 | 11.9 | 117 |
| 2006 | 10 | 119 |
| 2005 | 8.1 | 121 |
| 2004 | 7 | 121 |
| 2003 | 5.8 | 124 |
| 2002 | 7.4 | 116 |
| 2001 | 4.3 | 125 |
| 2000 | 4.6 | 120 |
| 1999 | 6 | 110 |
| 1998 | 10.2 | 102 |
| 1997 | 4.9 | 111 |
| 1996 | 2.8 | 118 |
| 1995 | 1.7 | 120 |
| 1994 | 1.2 | 118 |
| 1993 | 1.7 | 110 |
| 1992 | 1.1 | 108 |
| 1991 | 0.7 | 107 |
| 1990 | 0.7 | 104 |
| 1989 | 0.8 | 91 |
| 1988 | 1 | 88 |
| 1987 | 0.7 | 89 |
| 1986 | 0.8 | 88 |