sweater vest vs waistcoat

sweater vest

noun
  • A sleeveless sweater, commonly knit in argyle. 

waistcoat

noun
  • A sleeveless, collarless garment worn over a shirt and under a suit jacket. 

  • An ornamental garment worn under a doublet. 

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