Year	2011 U.S. Dollars
1960-01-01	13936
1961-01-01	14659
1962-01-01	15198
1963-01-01	15920
1964-01-01	16879
1965-01-01	17359
1966-01-01	17554
1967-01-01	18006
1968-01-01	18553
1969-01-01	19345
1970-01-01	20411
1971-01-01	20463
1972-01-01	20870
1973-01-01	21658
1974-01-01	22285
1975-01-01	22765
1976-01-01	22924
1977-01-01	22476
1978-01-01	22804
1979-01-01	23628
1980-01-01	23984
1981-01-01	23906
1982-01-01	24177
1983-01-01	24603
1984-01-01	25629
1985-01-01	26149
1986-01-01	26833
1987-01-01	27668
1988-01-01	28278
1989-01-01	28869
1990-01-01	28936
1991-01-01	28419
1992-01-01	27911
1993-01-01	27179
1994-01-01	28096
1995-01-01	29052
1996-01-01	29439
1997-01-01	30248
1998-01-01	31490
1999-01-01	32918
2000-01-01	34356
2001-01-01	34694
2002-01-01	35439
2003-01-01	36123
2004-01-01	37490
2005-01-01	38535
2006-01-01	39967
2007-01-01	41003
2008-01-01	40420
2009-01-01	38057
2010-01-01	40071
2011-01-01	41316