audience vs readership

audience

noun
  • The readership of a book or other written publication. 

  • A following. 

  • An audiencia (judicial court of the Spanish empire), or the territory administered by it. 

  • A widespread or nationwide viewing or listening public, as of a TV or radio network or program. 

  • A group of people within hearing; specifically, a large gathering of people listening to or watching a performance, speech, etc. 

  • A formal meeting with a state or religious dignitary. 

readership

noun
  • The collected readers of a publication. 

  • The role or office of a reader. 

How often have the words audience and readership occurred in a corpus of books? (source: Google Ngram Viewer )