| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2015 | 37.6 | 52 |
| 2014 | 3.9 | 128 |
| 2013 | 21.5 | 61 |
| 2012 | 49.9 | 46 |
| 2011 | 58.6 | 45 |
| 2010 | 15.8 | 75 |
| 2009 | -11.4 | 194 |
| 2008 | 20.8 | 76 |
| 2007 | 43.6 | 60 |
| 2006 | 2 | 131 |
| 2005 | 24.5 | 58 |
| 2004 | 14.9 | 54 |
| 2003 | 15.7 | 49 |
| 2002 | 7.6 | 61 |
| 2001 | 37 | 31 |
| 2000 | 47 | 31 |
| 1999 | 28.9 | 34 |
| 1998 | 49.9 | 23 |
| 1997 | 62 | 16 |
| 1996 | 21.8 | 33 |
| 1995 | 9.9 | 40 |
| 1994 | 8.1 | 40 |
| 1993 | 3.7 | 52 |
| 1992 | 6.3 | 35 |
| 1991 | 19.2 | 19 |
| 1990 | 4.5 | 38 |
| 1989 | 2.1 | 37 |
| 1988 | 0.9 | 53 |
| 1987 | 0.2 | 71 |
| 1986 | 0.2 | 69 |