Year	US Dollars, Sum Over Component Sub-periods
1988-01-01	-1585200000
1989-01-01	-1694200000
1990-01-01	553600000
1991-01-01	1192000000
1992-01-01	3160300000
1993-01-01	3889100000
1994-01-01	2330300000
1995-01-01	1276500000
1996-01-01	2662200000
1997-01-01	672300000
1998-01-01	-1485200000
1999-01-01	3326100000
2000-01-01	2552500000
2001-01-01	4115700000
2002-01-01	4984900000
2003-01-01	7343500000
2004-01-01	5743700000
2005-01-01	11125700000
2006-01-01	8176500000
2007-01-01	4234800000
2008-01-01	9058100000
2009-01-01	10550800000
2010-01-01	18436800000
2011-01-01	18890900000
2012-01-01	18129700000
2013-01-01	24216100000