Munro vs mountains

Munro

noun
  • Any Scottish mountain having a height of more than 3,000 feet; named after Sir Hugh Thomas Munro, Scottish mountaineer 

name
  • A Scottish surname from Scottish Gaelic, variant of Monroe. 

mountains

noun
  • mountain range 

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