How many Americans did Jonathan Kozol estimate were illiterate in his book Illiterate America (1985)?

Kozol said that as of 1984, 25 million Americans were functionally illiterate (reading not at all or at less than fifth grade level) and an additional 35 million were marginally illiterate (reading at less than ninth grade level).

The total of 60 million represented more than a third of the adult population.