garret vs mansard

garret

noun
  • An attic or semi-finished room just beneath the roof of a house. 

mansard

noun
  • The upper storey of a building, surrounded by such a roof 

  • A mansard roof 

adj
  • having two slopes on each side, the lower being steeper than the upper 

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