CREATE TABLE table_62663 ("County" TEXT, "Per capita income" TEXT, "Median household income" TEXT, "Median family income" TEXT, "Population" FLOAT, "Number of households" FLOAT)

Which Number of households has a County of cook, and Population smaller than 5,176?
SELECT AVG("Number of households") FROM table_62663 WHERE "County" = 'cook' AND "Population" < '5,176'
SELECT AVG("Number of households") FROM "table_62663" WHERE "County" = 'cook' AND "Population" < '5,176'