cognac vs whisky

cognac

noun
  • A brandy distilled from white wine in the region around Cognac in France. 

whisky

noun
  • A drink of this liquor. 

  • An alcoholic liquor distilled from fermented grain and usually aged in oak barrels. 

  • A light gig or carriage. 

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