French knickers vs G-string

French knickers

noun
  • A type of full-fitting women's underwear. 

G-string

noun
  • A scanty covering for the genitalia, with a thin strip of fabric that passes between the buttocks. 

  • On a stringed musical instrument, the string that produces the note of G. 

  • A type of loincloth or breechcloth. 

How often have the words French knickers and G-string occurred in a corpus of books? (source: Google Ngram Viewer )