| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 9.5 | 146 |
| 2015 | 9.7 | 172 |
| 2014 | 10 | 173 |
| 2013 | 9.7 | 178 |
| 2012 | 10 | 177 |
| 2011 | 8.9 | 181 |
| 2010 | 8 | 182 |
| 2009 | 6.8 | 184 |
| 2008 | 7.7 | 180 |
| 2007 | 6.9 | 181 |
| 2006 | 6.3 | 181 |
| 2005 | 5.6 | 180 |
| 2004 | 4.9 | 181 |
| 2003 | 4.1 | 180 |
| 2002 | 4 | 179 |
| 2001 | 3.8 | 176 |
| 2000 | 3.3 | 176 |
| 1999 | 3.2 | 172 |
| 1998 | 3.2 | 172 |
| 1997 | 3.4 | 172 |
| 1996 | 3 | 173 |
| 1995 | 2.8 | 173 |
| 1994 | 2.7 | 165 |