T-shirt vs saddle blanket

T-shirt

noun
  • A lightweight shirt without buttons, usually with short sleeves and no collar. Often made of cotton and frequently bears a picture or slogan. 

saddle blanket

noun
  • a blanket that is placed under a saddle (as a cushion and to protect the horse's back); a numnah 

How often have the words T-shirt and saddle blanket occurred in a corpus of books? (source: Google Ngram Viewer )