siren suit vs swimming trunks

siren suit

noun
  • A one-piece garment for the whole body, originally designed to be put on while making one's way to an air-raid shelter. 

swimming trunks

noun
  • A pair of shorts or briefs worn for swimming or bathing. 

How often have the words siren suit and swimming trunks occurred in a corpus of books? (source: Google Ngram Viewer )