Year	US Dollars
1960	49.79139
1961	49.13043
1962	46.40209
1963	47.76797
1964	38.77172
1965	47.92431
1966	42.25941
1967	25.74499
1968	22.11559
1969	19.16927
1970	21.23739
1971	23.5321
1972	27.11881
1973	56.75412
1974	34.82085
1975	135.30536
1976	182.09454
1977	220.70302
1978	243.813
1979	312.91074
1980	230.05672
1981	195.25025
1982	212.71149
1983	327.64433
1984	301.97404
1985	467.37539
1986	450.59548
1987	286.28978
1988	279.39218
1989	263.78044
1990	294.397
1991	353.49767
1992	403.23444
1993	240.67098
1994	229.14985
1995	60.52119
1996	389.45186