What's the Percentage of the Population Literate?

There was a linguistic melting pot within the roman empire. While latin does wipe out a lot of the languages of the western empire, it's also true that in britain, they don't wipe out the native language. These two languages kind of run parallel in different halfs of the empire. A case on the next question, i believe, apologies for butchering your name here bybe cedrics. I would like to know what percentage of the population was literate. There is a book called ancient literacy by william harris, which is about greece and rome. And he says between five % in the western provinces, or perhaps up to about 20