Year	current US$
1976	27210313808.3784
1977	29247654315.512413
1978	19465216413.47003
1979	25949577014.596394
1980	20970377742.196285
1989	22284556835.066822
1990	29005277070.534943
1993	22771282494.894894
1994	25494455098.200516
1995	33942064577.430386
1996	48371838780.053444
1997	41164859643.82083
1998	32428822270.74236
1999	41876098178.33173
2000	41577176586.98308