| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 58.8 | 29 |
| 2015 | 57.3 | 31 |
| 2014 | 57.3 | 34 |
| 2013 | 59 | 33 |
| 2012 | 54.9 | 33 |
| 2011 | 55.1 | 33 |
| 2010 | 49.6 | 31 |
| 2009 | 48 | 32 |
| 2008 | 44.7 | 36 |
| 2007 | 35.2 | 40 |
| 2006 | 24.4 | 46 |
| 2005 | 19.8 | 47 |
| 2004 | 18.7 | 45 |
| 2003 | 18.9 | 43 |
| 2002 | 18.1 | 39 |
| 2001 | 17.2 | 43 |
| 2000 | 18.8 | 41 |
| 1999 | 20.6 | 37 |
| 1998 | 21.1 | 38 |
| 1997 | 32.6 | 27 |
| 1996 | 39.4 | 25 |
| 1995 | 38.5 | 23 |
| 1994 | 36.1 | 23 |
| 1993 | 31.6 | 27 |
| 1992 | 29.6 | 28 |
| 1991 | 26 | 28 |
| 1990 | 22.1 | 28 |
| 1989 | 19.4 | 30 |
| 1988 | 18.1 | 27 |
| 1987 | 17 | 28 |
| 1986 | 16.4 | 30 |