As used in this subchapter, unless the context otherwise requires, “farmers of low income” means persons or families who, at the time of their admission to occupancy in a dwelling of a housing authority:
(1) Live under unsafe or unsanitary housing conditions;
(2) Derive their principal income from operating or working upon a farm; and
(3) Had an aggregate average annual net income for the three (3) years preceding their admission that was less than the amount determined by the housing authority to be necessary, within its area of operation, to enable them, without financial assistance, to obtain decent, safe, and sanitary housing, without overcrowding.