Jerusalem artichoke vs sunchoke

Jerusalem artichoke

noun
  • The tuber of this plant, eaten as a vegetable. 

  • A variety of sunflower, Helianthus tuberosus, native to North America, having yellow flower heads and edible tubers. 

sunchoke

noun
  • Synonym of Jerusalem artichoke 

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