| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 13.7 | 82 |
| 2014 | 23.9 | 62 |
| 2013 | 30.4 | 52 |
| 2012 | 25.7 | 70 |
| 2011 | 26.9 | 61 |
| 2010 | 21.9 | 61 |
| 2009 | 16 | 71 |
| 2008 | 21.4 | 75 |
| 2007 | 13.6 | 89 |
| 2006 | 15.1 | 79 |
| 2005 | 8.3 | 81 |
| 2004 | 3.5 | 96 |
| 2003 | 4 | 82 |
| 2002 | 1.8 | 98 |
| 2001 | 3.1 | 78 |
| 2000 | 2.6 | 77 |
| 1999 | 2.4 | 85 |
| 1998 | 1.6 | 100 |
| 1997 | 1.3 | 99 |
| 1996 | 1.4 | 82 |
| 1995 | 1.6 | 69 |
| 1994 | 1.5 | 67 |
| 1993 | 1 | 75 |
| 1992 | 0.1 | 111 |
| 1991 | 0.3 | 81 |
| 1990 | 0.4 | 76 |
| 1989 | 0.4 | 68 |
| 1988 | 0.5 | 62 |
| 1987 | 0.5 | 58 |
| 1986 | 0.4 | 51 |