bathrobe vs housecoat

bathrobe

noun
  • A robe usually made of terrycloth intended to be worn when one is still damp from bathing or when there is no immediate need to dress fully. 

housecoat

noun
  • A bathrobe or dressing gown. 

  • A longish dress-like garment of one piece, fastening down the front, worn about the house. 

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