| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 2.7 | 59 |
| 2015 | 2.8 | 132 |
| 2014 | 4.9 | 116 |
| 2013 | 14.3 | 75 |
| 2012 | 28.7 | 64 |
| 2011 | 32.6 | 58 |
| 2010 | 13 | 82 |
| 2009 | 11.1 | 84 |
| 2008 | -.1 | 191 |
| 2007 | 1.1 | 155 |
| 2006 | 1.2 | 142 |
| 2005 | 2.3 | 118 |
| 2004 | 0.2 | 159 |
| 2003 | -.7 | 187 |
| 2002 | 0 | 166 |
| 2001 | -1.1 | 184 |
| 2000 | 0.2 | 149 |
| 1999 | 0.7 | 112 |
| 1998 | 0.6 | 126 |
| 1997 | 0.2 | 143 |
| 1996 | 3.5 | 60 |
| 1995 | 0.1 | 145 |
| 1994 | 0 | 157 |
| 1993 | 0.1 | 124 |
| 1992 | 0.4 | 83 |
| 1991 | 0 | 132 |
| 1990 | 0.1 | 116 |
| 1989 | 0 | 108 |
| 1988 | 0.2 | 80 |
| 1987 | -.1 | 135 |
| 1986 | -.1 | 132 |