Year US Dollars adjusted for inflation) 1960 349.04955 1961 387.35691 1962 398.17863 1963 413.2159 1964 463.63622 1965 520.72676 1966 548.71792 1967 553.49852 1968 554.31597 1969 587.44512 1970 579.32349 1971 560.73244 1972 586.86329 1973 594.63114 1974 609.27605 1975 610.20883 1976 584.59177 1977 611.84009 1978 664.15134 1979 614.01108 1980 683.3489 1981 639.26698 1982 594.58168 1983 541.73096 1984 551.06827 1985 561.52055 1986 551.60267 1987 536.85264 1988 555.27464 1989 561.44773 1990 545.2061 1991 528.09575 1992 495.45339 1993 411.18144 1994 461.57703 1995 484.9355 1996 512.87984 1997 568.98419 1998 538.73404 1999 535.32245 2000 515.66977 2001 493.2483 2002 475.6992 2003 486.30919 2004 483.76547 2005 476.67155 2006 482.85964 2007 480.77591 2008 478.36178 2009 481.96028 2010 487.92389 2011 498.2429 2012 508.54004 2013 514.94497 2014 531.1561 2015 545.57788 2016 560.69765 2017 577.38226