Year	2011 U.S. Dollars
1975-01-01	18220
1976-01-01	18228
1977-01-01	18220
1978-01-01	18698
1979-01-01	19979
1980-01-01	20990
1981-01-01	21170
1982-01-01	21693
1983-01-01	22217
1984-01-01	22785
1985-01-01	23440
1986-01-01	23981
1987-01-01	24747
1988-01-01	25964
1989-01-01	27184
1990-01-01	27201
1991-01-01	25429
1992-01-01	24406
1993-01-01	24091
1994-01-01	24864
1995-01-01	25750
1996-01-01	26582
1997-01-01	28148
1998-01-01	29486
1999-01-01	30567
2000-01-01	32128
2001-01-01	32787
2002-01-01	33307
2003-01-01	33897
2004-01-01	35192
2005-01-01	36095
2006-01-01	37543
2007-01-01	39378
2008-01-01	39310
2009-01-01	35782
2010-01-01	36802
2011-01-01	37636