| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 47.4 | 71 |
| 2015 | 44.1 | 83 |
| 2014 | 40.2 | 84 |
| 2013 | 39.1 | 88 |
| 2012 | 38.3 | 90 |
| 2011 | 37.6 | 90 |
| 2010 | 35.8 | 92 |
| 2009 | 32.3 | 88 |
| 2008 | 32.4 | 88 |
| 2007 | 30.2 | 88 |
| 2006 | 28.9 | 88 |
| 2005 | 28.1 | 85 |
| 2004 | 27 | 86 |
| 2003 | 26.5 | 84 |
| 2002 | 26.4 | 83 |
| 2001 | 24.2 | 84 |
| 2000 | 22.4 | 83 |
| 1999 | 22 | 80 |
| 1998 | 21.7 | 80 |
| 1997 | 20.7 | 80 |
| 1996 | 20.8 | 78 |
| 1995 | 20.4 | 79 |
| 1994 | 19.5 | 75 |
| 1993 | 19.6 | 74 |
| 1992 | 19.1 | 70 |
| 1991 | 20.7 | 65 |
| 1990 | 19.1 | 68 |
| 1989 | 18.9 | 56 |
| 1988 | 20.3 | 54 |
| 1987 | 24.9 | 51 |
| 1986 | 23.4 | 50 |