apartment vs studio apartment

apartment

noun
  • A complete domicile occupying only part of a building, especially one for rent; a flat. 

  • A conceptual space used for separation in the threading architecture. Objects in one apartment cannot directly access those in another, but must use a proxy. 

studio apartment

noun
  • A small apartment that combines a number of rooms, often the living room, bedroom, and kitchen, into a single room. 

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