| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 7.2 | 51 |
| 2015 | -6.5 | 195 |
| 2014 | 16.8 | 79 |
| 2013 | 10.8 | 82 |
| 2012 | 17.9 | 75 |
| 2011 | 11.2 | 90 |
| 2010 | 25.9 | 57 |
| 2009 | 18.7 | 66 |
| 2008 | 18.7 | 80 |
| 2007 | 34.3 | 62 |
| 2006 | 22.1 | 69 |
| 2005 | 31.3 | 50 |
| 2004 | 10.9 | 62 |
| 2003 | 10.4 | 58 |
| 2002 | 3.4 | 78 |
| 2001 | 5.9 | 61 |
| 2000 | 4.2 | 64 |
| 1999 | 3.1 | 77 |
| 1998 | 5.8 | 63 |
| 1997 | 2.7 | 78 |
| 1996 | 1.5 | 79 |
| 1995 | 2 | 67 |
| 1994 | 2.1 | 61 |
| 1993 | 1.6 | 64 |
| 1992 | 0.8 | 71 |