| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 23.9 | 89 |
| 2015 | 22.6 | 108 |
| 2014 | 25.7 | 103 |
| 2013 | 25.3 | 107 |
| 2012 | 22.6 | 107 |
| 2011 | 21.3 | 109 |
| 2010 | 19.4 | 114 |
| 2009 | 17.9 | 106 |
| 2008 | 16.8 | 109 |
| 2007 | 16.1 | 107 |
| 2006 | 14.8 | 108 |
| 2005 | 13.8 | 104 |
| 2004 | 13.3 | 103 |
| 2003 | 13.2 | 102 |
| 2002 | 13 | 100 |
| 2001 | 12.7 | 101 |
| 2000 | 10.9 | 104 |
| 1999 | 11.6 | 97 |
| 1998 | 14 | 93 |
| 1997 | 11.2 | 98 |
| 1996 | 11 | 97 |
| 1995 | 9.3 | 99 |
| 1994 | 9.3 | 93 |
| 1993 | 9.2 | 91 |
| 1992 | 9.4 | 86 |
| 1991 | 8.9 | 87 |
| 1990 | 8.6 | 84 |
| 1989 | 8.9 | 71 |
| 1988 | 9.8 | 70 |
| 1987 | 10 | 69 |
| 1986 | 12.4 | 66 |