 In the district of Huambo, between 1968 and 1970 white-owned land more than doubled from 249,039 hectares to 526,270 hectares.Native-owned land decreased by 36.5%.The average African farm's gross income declined between 1964 and 1970 from $98.00 to $35.00 Portuguese petroleum-production began in Congo basin in the 1960s, and in the exclave of Cabinda in 1968.