| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 11.6 | 45 |
| 2015 | 11.8 | 86 |
| 2014 | 11.7 | 85 |
| 2013 | 13.5 | 76 |
| 2012 | 12.6 | 91 |
| 2011 | 11.4 | 89 |
| 2010 | 8.5 | 94 |
| 2009 | 7 | 95 |
| 2008 | 7.5 | 112 |
| 2007 | 8.6 | 98 |
| 2006 | 6.4 | 94 |
| 2005 | 5.4 | 93 |
| 2004 | 3.2 | 99 |
| 2003 | 0.2 | 154 |
| 2002 | -10.2 | 193 |
| 2001 | -9.4 | 188 |
| 2000 | -7.9 | 183 |
| 1999 | 1.5 | 95 |
| 1998 | 6.7 | 59 |
| 1997 | 0.8 | 107 |
| 1996 | 0.8 | 104 |
| 1995 | 0.8 | 94 |
| 1994 | 0.7 | 89 |
| 1993 | 1.4 | 67 |
| 1992 | 0.9 | 68 |
| 1991 | 0.9 | 61 |
| 1990 | 0.5 | 71 |
| 1989 | 0.8 | 54 |
| 1988 | 3.3 | 32 |
| 1987 | 1.5 | 34 |
| 1986 | 0.7 | 46 |