The book from Catherine Hezser, Jewish Literacy in Roman world does good job in analyzing the level of education and literacy among Jews, Roman settlers in the Judea and Palestine, and who the education changed through the antiquity. It is often estimated that only 1 in 7 could write and write during Roman Empire and this included soldiers who would have to at least sign their names on the official documents. What is another interesting fact her book at the page 503 that "at least ninety percent of the Jewish population of Roman Palestine could merely write own name or not write and read at all must lead to a new assessment of our understanding of ancient Judaism as a 'book-religion'".
Before the Roman takeover of Jerusalem, only handful of priests and high level of aristocracy could read. Majority of peasants in the countryside were illiterate and had to rely on oral tradition on various interpretation of the OT.