| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 8 | 147 |
| 2015 | 7.3 | 175 |
| 2014 | 9.3 | 176 |
| 2013 | 8.9 | 180 |
| 2012 | 8 | 182 |
| 2011 | 7.9 | 186 |
| 2010 | 7.2 | 185 |
| 2009 | 7 | 183 |
| 2008 | 7 | 182 |
| 2007 | 5.8 | 184 |
| 2006 | 5 | 183 |
| 2005 | 4.6 | 182 |
| 2004 | 4.3 | 182 |
| 2003 | 3.6 | 182 |
| 2002 | 2.8 | 183 |
| 2001 | 2.4 | 178 |
| 2000 | 2.1 | 180 |
| 1999 | 2.7 | 175 |
| 1998 | 2.7 | 175 |
| 1997 | 2.6 | 176 |
| 1996 | 2.8 | 174 |
| 1995 | 2.9 | 171 |
| 1994 | 2.4 | 169 |
| 1993 | 3.1 | 157 |
| 1992 | 3.3 | 153 |
| 1991 | 2.9 | 153 |
| 1990 | 3.1 | 150 |
| 1989 | 2.5 | 133 |
| 1988 | 2.6 | 128 |
| 1987 | 2.5 | 127 |
| 1986 | 2 | 129 |