inn vs onsen

inn

noun
  • Any establishment where travellers can procure lodging, food, and drink. 

  • A tavern. 

  • One of the colleges (societies or buildings) in London, for students of the law barristers. 

onsen

noun
  • A Japanese-style resort hotel at a natural hot spring, offering on-site bathing. 

  • A (Japanese) hot spring. 

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