| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 3.6 | 88 |
| 2015 | 3.8 | 93 |
| 2014 | 3.7 | 96 |
| 2013 | 3.6 | 98 |
| 2012 | 3.2 | 99 |
| 2011 | 2 | 109 |
| 2010 | 1 | 121 |
| 2006 | 1.6 | 102 |
| 2005 | 1.3 | 105 |
| 2004 | 2.6 | 85 |
| 2003 | 1.9 | 89 |
| 2002 | 6.8 | 63 |
| 2001 | 2.9 | 76 |
| 2000 | 3.5 | 71 |
| 1999 | 2.6 | 78 |
| 1998 | 3.1 | 72 |
| 1997 | 3.1 | 72 |
| 1996 | 2.9 | 70 |
| 1995 | 2.6 | 70 |
| 1994 | 2.5 | 69 |
| 1993 | 2.5 | 73 |
| 1992 | 3 | 62 |
| 1991 | 3.8 | 60 |
| 1990 | 4.2 | 59 |
| 1989 | 4.1 | 56 |
| 1988 | 4.1 | 54 |
| 1987 | 3.9 | 55 |
| 1986 | 3.4 | 51 |