Year US Dollars adjusted for inflation) 1960 897.52352 1961 923.79535 1962 906.90173 1963 932.44493 1964 892.52051 1965 906.55035 1966 891.40988 1967 935.86205 1968 924.52065 1969 1006.62167 1970 1194.17139 1971 1257.98687 1972 1317.31164 1973 1306.50634 1974 1347.44433 1975 1279.40998 1976 1246.04643 1977 1126.00339 1978 1062.62602 1979 1062.99421 1980 1175.13524 1981 1274.68338 1982 1259.19598 1983 1230.39367 1984 1161.40584 1985 1196.6352 1986 1178.55863 1987 1151.44671 1988 1198.30453 1989 1222.64726 1990 1272.05103 1991 1309.005 1992 1164.2536 1993 1152.45044 1994 1234.96618 1995 1214.69346 1996 1317.50986 1997 1330.67629 1998 1347.9718 1999 1317.96884 2000 1261.16309 2001 1264.43062 2002 1139.59007 2003 935.93016 2004 871.66711 2005 811.56295 2006 772.47259 2007 732.76998 2008 593.12725 2009 652.28873 2010 719.97952 2011 813.83401 2012 913.53063 2013 942.03866 2014 939.78027 2015 933.50327 2016 917.56372 2017 927.39866