| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 79.3 | 27 |
| 2015 | 56.4 | 42 |
| 2014 | 57.4 | 40 |
| 2013 | 37.4 | 45 |
| 2012 | 32.2 | 60 |
| 2011 | 20.1 | 71 |
| 2010 | 10.7 | 88 |
| 2009 | 20.6 | 63 |
| 2008 | 13.4 | 93 |
| 2007 | 29.2 | 66 |
| 2006 | 27.1 | 63 |
| 2005 | 16.6 | 65 |
| 2004 | 5.9 | 80 |
| 2003 | 4.9 | 79 |
| 2002 | 17.7 | 43 |
| 2001 | 7.6 | 57 |
| 2000 | 14.9 | 39 |
| 1999 | 12.5 | 44 |
| 1998 | 22.9 | 37 |
| 1997 | 12.2 | 46 |
| 1996 | 15.2 | 36 |
| 1995 | 14.8 | 33 |
| 1994 | 15.9 | 28 |
| 1993 | 12.4 | 27 |
| 1992 | 2.3 | 45 |
| 1991 | 5.4 | 34 |
| 1990 | 5.3 | 36 |
| 1989 | 5.6 | 34 |
| 1988 | 9.4 | 21 |
| 1987 | 3.1 | 29 |
| 1986 | 1.3 | 36 |