| 时间 | 值 （美元） | 世界排名 |
|---|---|---|
| 2016 | 30762 | 3 |
| 2015 | 30326 | 5 |
| 2014 | 29964 | 5 |
| 2013 | 29617 | 5 |
| 2012 | 29669 | 5 |
| 2011 | 29429 | 5 |
| 2010 | 28745 | 6 |
| 2009 | 28546 | 5 |
| 2008 | 29052 | 6 |
| 2007 | 28301 | 7 |
| 2006 | 27180 | 7 |
| 2005 | 26741 | 7 |
| 2004 | 25927 | 7 |
| 2003 | 24946 | 7 |
| 2002 | 24220 | 8 |
| 2001 | 23782 | 8 |
| 2000 | 23338 | 7 |
| 1999 | 22680 | 7 |
| 1998 | 21754 | 7 |
| 1997 | 20957 | 9 |
| 1996 | 20587 | 9 |
| 1995 | 20194 | 9 |
| 1994 | 19539 | 9 |
| 1993 | 19283 | 9 |
| 1992 | 19103 | 10 |
| 1991 | 18887 | 10 |
| 1990 | 18926 | 8 |
| 1989 | 18439 | 10 |
| 1988 | 17904 | 10 |
| 1987 | 17611 | 10 |
| 1986 | 17503 | 8 |