summer house vs wigwam

summer house

wigwam

noun
  • A dwelling having an arched framework overlaid with bark, hides, or mats, used by Native Americans in the northeastern United States. 

verb
  • To dry (flax or straw) by standing it outside in the shape of a wigwam. 

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