Year US Dollars adjusted for inflation) 1960 696.27693 1961 692.45299 1962 715.3433 1963 690.11908 1964 659.74431 1965 651.09541 1966 627.46175 1967 620.74477 1968 606.51012 1969 635.70678 1970 634.16906 1971 606.18267 1972 598.84571 1973 535.66548 1974 549.32808 1975 585.86944 1976 591.14508 1977 592.73963 1978 578.8449 1979 445.98348 1980 410.53086 1981 405.9833 1982 418.16294 1983 472.31658 1984 469.83692 1985 556.7753 1986 518.62083 1987 490.77932 1988 548.87544 1989 557.3476 1990 517.13464 1991 543.63884 1992 568.73434 1993 464.2855 1994 494.99987 1995 484.75809 1996 479.04213 1997 489.09526 1998 505.16209 1999 484.08256 2000 462.5286 2001 497.3468 2002 519.27665 2003 573.33437 2004 737.98753 2005 835.19554 2006 812.0086 2007 811.01628 2008 808.889 2009 815.96805 2010 896.56973 2011 867.99906 2012 914.11865 2013 934.70255 2014 967.10278 2015 962.65592 2016 874.76707 2017 823.43489