| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2014 | 22.4 | 164 |
| 2013 | 21.2 | 168 |
| 2012 | 20.9 | 169 |
| 2011 | 24 | 170 |
| 2010 | 21.5 | 168 |
| 2009 | 21.5 | 167 |
| 2008 | 22.6 | 163 |
| 2007 | 19.7 | 163 |
| 2006 | 14.1 | 167 |
| 2005 | 12.5 | 165 |
| 2004 | 12.7 | 164 |
| 2003 | 11.1 | 164 |
| 2002 | 8.4 | 166 |
| 2001 | 7.5 | 164 |
| 2000 | 7.2 | 165 |
| 1999 | 8.2 | 160 |
| 1998 | 7.1 | 164 |
| 1997 | 6.4 | 165 |
| 1996 | 6.8 | 164 |
| 1995 | 7 | 157 |
| 1994 | 5.8 | 156 |
| 1993 | 6.6 | 146 |
| 1992 | 5.3 | 147 |
| 1991 | 4.7 | 146 |
| 1990 | 4.7 | 140 |
| 1989 | 3.8 | 127 |
| 1988 | 3.8 | 122 |
| 1987 | 3.5 | 121 |
| 1986 | 3 | 122 |