smetana vs sour cream

smetana

noun
  • A form of soured cream or crème fraîche from Central and Eastern Europe. 

sour cream

noun
  • Cream which has been treated with a benign bacterium to turn it slightly sour, often used as a condiment, or a topping for baked potatoes. 

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