| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 6.9 | 106 |
| 2014 | 7.2 | 102 |
| 2013 | 5.5 | 107 |
| 2012 | 5.3 | 121 |
| 2011 | 6.5 | 116 |
| 2010 | 5.4 | 105 |
| 2009 | 7.4 | 93 |
| 2008 | 0.2 | 176 |
| 2007 | 1.9 | 141 |
| 2006 | 0.6 | 158 |
| 2005 | 2.4 | 114 |
| 2004 | 0.7 | 137 |
| 2003 | 3.3 | 90 |
| 2002 | 5 | 70 |
| 2001 | -.1 | 178 |
| 2000 | 1.6 | 91 |
| 1999 | -.2 | 177 |
| 1998 | 2.2 | 89 |
| 1997 | 0.8 | 115 |
| 1996 | 1 | 94 |
| 1995 | 0.1 | 140 |
| 1994 | -.1 | 168 |
| 1993 | 0.1 | 138 |
| 1992 | 0.3 | 87 |
| 1991 | -.1 | 151 |
| 1990 | -1.1 | 147 |
| 1989 | -.9 | 143 |
| 1988 | 0.9 | 49 |
| 1987 | 1.2 | 38 |
| 1986 | -.9 | 138 |