French knickers vs pantalettes

French knickers

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

pantalettes

noun
  • A form of long underpants with a frill at the bottom of each leg. 

  • A removable kind of ruffle worn at the feet of women's drawers. 

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