| 时间 | 值 （美元） | 世界排名 |
|---|---|---|
| 2015 | 36351 | 25 |
| 2014 | 34789 | 32 |
| 2013 | 35938 | 34 |
| 2012 | 38898 | 31 |
| 2011 | 40072 | 32 |
| 2010 | 40831 | 25 |
| 2009 | 39388 | 27 |
| 2008 | 39686 | 32 |
| 2007 | 44711 | 23 |
| 2006 | 41820 | 22 |
| 2005 | 41154 | 18 |
| 2004 | 35192 | 24 |
| 2003 | 31947 | 22 |
| 2002 | 30210 | 15 |
| 1993 | 18728 | 20 |
| 1992 | 16752 | 27 |
| 1991 | 15945 | 26 |
| 1990 | 15051 | 27 |
| 1989 | 13048 | 29 |
| 1988 | 11527 | 29 |
| 1987 | 10828 | 31 |
| 1986 | 9724 | 30 |