bedsit vs efficiency apartment

bedsit

noun
  • A form of rented accommodation consisting of a single room for use as both sitting room and bedroom; there may also be a small kitchen area and washing and toilet facilities, but these amenities are more commonly outside the room and shared by several tenants. 

efficiency apartment

noun
  • bachelor apartment 

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