Year	US Dollars adjusted for inflation)
1970	16860
1971	16750
1972	15790
1973	16640
1974	13590
1975	11360
1976	11700
1977	12480
1978	13970
1979	17210
1980	18050
1981	17190
1982	17660
1983	18510
1984	18530
1985	18950
1986	19020
1987	19930
1988	20060
1989	22220
1990	20640
1991	19720
1992	17950
1993	17390
1994	17740
1995	17110
1996	16740
1997	16620
1998	16710
1999	18430
2000	19090
2001	18530
2002	18380
2003	18380
2004	18710