Year	2011 U.S. Dollars
1971-01-01	36966
1972-01-01	39491
1973-01-01	41506
1974-01-01	43678
1975-01-01	44802
1976-01-01	46795
1977-01-01	48436
1978-01-01	50392
1979-01-01	51579
1980-01-01	53512
1981-01-01	54753
1982-01-01	55916
1983-01-01	57104
1984-01-01	59453
1985-01-01	61463
1986-01-01	62026
1987-01-01	62474
1988-01-01	63434
1989-01-01	64171
1990-01-01	64160
1991-01-01	65013
1992-01-01	66543
1993-01-01	67780
1994-01-01	69724
1995-01-01	70309
1996-01-01	70989
1997-01-01	71645
1998-01-01	72036
1999-01-01	72816
2000-01-01	73916
2001-01-01	74227
2002-01-01	74407
2003-01-01	74324
2004-01-01	74063
2005-01-01	73663
2006-01-01	73729
2007-01-01	74052
2008-01-01	74844
2009-01-01	77209
2010-01-01	79220
2011-01-01	81417