jerkin vs knitwear

jerkin

noun
  • A type of men's garment popular in the sixteenth and seventeenth centuries: a close-fitting collarless jacket, with or without sleeves. 

  • A sleeveless jacket, usually leather; a long waistcoat. 

knitwear

noun
  • knitted garments 

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