| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 37.6 | 134 |
| 2015 | 38.1 | 156 |
| 2014 | 36.3 | 159 |
| 2013 | 31.5 | 163 |
| 2012 | 27.1 | 164 |
| 2011 | 26.7 | 166 |
| 2010 | 22.4 | 167 |
| 2009 | 20.8 | 168 |
| 2008 | 17.9 | 167 |
| 2007 | 19.3 | 164 |
| 2006 | 12.8 | 169 |
| 2005 | 13.9 | 164 |
| 2004 | 12.1 | 165 |
| 2003 | 4.2 | 179 |
| 2002 | 4.8 | 177 |
| 2001 | 5.1 | 171 |
| 2000 | 5.7 | 169 |
| 1999 | 5.6 | 166 |
| 1998 | 4.6 | 169 |
| 1997 | 4.8 | 167 |
| 1986 | 7.5 | 116 |