| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | -14.6 | 196 |
| 2014 | 9.6 | 93 |
| 2013 | 9.9 | 87 |
| 2012 | 8.9 | 100 |
| 2011 | 7.8 | 107 |
| 2010 | 1.6 | 144 |
| 2009 | 2.6 | 121 |
| 2008 | 17.9 | 82 |
| 2007 | 17.6 | 83 |
| 2006 | 29.1 | 61 |
| 2005 | 10.5 | 75 |
| 2004 | 8.7 | 70 |
| 2003 | 5.2 | 77 |
| 2002 | 2.2 | 91 |
| 2001 | 0.8 | 115 |
| 2000 | 3.6 | 67 |
| 1999 | 4.5 | 68 |
| 1998 | 1.8 | 97 |
| 1997 | 3.3 | 74 |
| 1996 | 20.5 | 34 |
| 1995 | 4.3 | 50 |
| 1994 | 2.1 | 62 |
| 1993 | -2.8 | 173 |
| 1992 | 8.7 | 29 |
| 1991 | 6.2 | 33 |
| 1990 | -1.8 | 150 |
| 1989 | 1.8 | 41 |
| 1988 | 2.2 | 36 |
| 1987 | -.4 | 138 |
| 1986 | -.3 | 134 |