Year US Dollars adjusted for inflation) 1960 612.25519 1961 622.18383 1962 666.65821 1963 708.6353 1964 689.26691 1965 716.00677 1966 693.11119 1967 674.43239 1968 658.06781 1969 604.66329 1970 605.90976 1971 622.73876 1972 574.43395 1973 463.48817 1974 490.29275 1975 463.34692 1976 453.36388 1977 474.68501 1978 523.25373 1979 544.64093 1980 517.33179 1981 505.69648 1982 499.29373 1983 462.06172 1984 373.42688 1985 390.88884 1986 404.01805 1987 392.87943 1988 407.93785 1989 399.62464 1990 382.48594 1991 379.73707 1992 343.51296 1993 336.94478 1994 338.59244 1995 335.48075 1996 334.84558 1997 331.89651 1998 353.41724 1999 338.84771 2000 322.14989 2001 332.75554 2002 330.54816 2003 335.66823 2004 323.96997 2005 326.33171 2006 332.71088 2007 330.63321 2008 349.00468 2009 333.69029 2010 348.15151 2011 342.74833 2012 368.94269 2013 373.73685 2014 386.7258 2015 388.31619 2016 392.14894 2017 395.93729