| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 31.6 | 46 |
| 2015 | 34.6 | 44 |
| 2014 | 38.9 | 47 |
| 2013 | 41.2 | 46 |
| 2012 | 44.9 | 40 |
| 2011 | 45.9 | 39 |
| 2010 | 41.9 | 39 |
| 2009 | 35.9 | 42 |
| 2008 | 32.9 | 44 |
| 2007 | 35.3 | 38 |
| 2006 | 35.1 | 35 |
| 2005 | 35.7 | 32 |
| 2004 | 31 | 34 |
| 2003 | 25.7 | 37 |
| 2002 | 17.7 | 41 |
| 2001 | 18 | 41 |
| 2000 | 18.9 | 39 |
| 1999 | 17.4 | 41 |
| 1998 | 19.1 | 41 |
| 1997 | 24.1 | 35 |
| 1996 | 25.9 | 35 |
| 1995 | 32.9 | 29 |
| 1994 | 34.8 | 25 |
| 1993 | 32.5 | 25 |
| 1992 | 36.8 | 24 |
| 1991 | 38.7 | 22 |
| 1990 | 43.6 | 21 |
| 1989 | 54.4 | 17 |
| 1988 | 53 | 17 |
| 1987 | 43.6 | 18 |
| 1986 | 30.4 | 19 |