| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 12.7 | 43 |
| 2015 | 27.8 | 61 |
| 2014 | 20.7 | 67 |
| 2013 | 19.9 | 67 |
| 2012 | 17.9 | 74 |
| 2011 | 21 | 69 |
| 2010 | 18.4 | 66 |
| 2009 | 39 | 50 |
| 2008 | 103 | 35 |
| 2007 | 138.8 | 32 |
| 2006 | 78.7 | 37 |
| 2005 | 41 | 47 |
| 2004 | 30.7 | 39 |
| 2003 | 21 | 41 |
| 2002 | 9 | 57 |
| 2001 | 8.1 | 55 |
| 2000 | 10 | 46 |
| 1999 | 8.2 | 52 |
| 1998 | 5.4 | 66 |
| 1997 | 5 | 61 |
| 1996 | 1.1 | 90 |
| 1995 | 0.9 | 92 |
| 1994 | 1.1 | 77 |
| 1993 | 0.4 | 96 |
| 1992 | 0.4 | 78 |
| 1991 | 0.6 | 68 |
| 1990 | 0 | 119 |