| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 27.5 | 136 |
| 2015 | 26.2 | 162 |
| 2014 | 23.7 | 163 |
| 2013 | 21.9 | 167 |
| 2012 | 22.7 | 167 |
| 2011 | 23.5 | 171 |
| 2010 | 20.3 | 169 |
| 2009 | 14.9 | 171 |
| 2008 | 13.7 | 173 |
| 2007 | 12 | 172 |
| 2006 | 9.4 | 173 |
| 2005 | 10.1 | 171 |
| 2004 | 8.9 | 171 |
| 2003 | 7.3 | 170 |
| 2002 | 6.4 | 170 |
| 2001 | 5.7 | 169 |
| 2000 | 5.5 | 170 |
| 1999 | 5 | 169 |
| 1998 | 4.4 | 170 |
| 1997 | 4 | 171 |
| 1996 | 3.5 | 170 |
| 1995 | 3.2 | 169 |
| 1994 | 3 | 163 |
| 1993 | 2.6 | 160 |
| 1992 | 3.1 | 155 |
| 1991 | 2.7 | 155 |
| 1990 | 3.1 | 148 |
| 1989 | 3 | 130 |
| 1988 | 3.4 | 123 |
| 1987 | 2.9 | 124 |
| 1986 | 2.7 | 125 |