Year	2011 U.S. Dollars
1970-01-01	12457
1971-01-01	12886
1972-01-01	13564
1973-01-01	14101
1974-01-01	14231
1975-01-01	14188
1976-01-01	14432
1977-01-01	15134
1978-01-01	16001
1979-01-01	16433
1980-01-01	16735
1981-01-01	16952
1982-01-01	17040
1983-01-01	16799
1984-01-01	17232
1985-01-01	17525
1986-01-01	17590
1987-01-01	18228
1988-01-01	18866
1989-01-01	20021
1990-01-01	21551
1991-01-01	21767
1992-01-01	22379
1993-01-01	22784
1994-01-01	24041
1995-01-01	26218
1996-01-01	27991
1997-01-01	30723
1998-01-01	32774
1999-01-01	35632
2000-01-01	38429
2001-01-01	39638
2002-01-01	41238
2003-01-01	42273
2004-01-01	43406
2005-01-01	44720
2006-01-01	45981
2007-01-01	47250
2008-01-01	45105
2009-01-01	41661
2010-01-01	41371
2011-01-01	41537