bolthole vs holiday home

bolthole

noun
  • A second home, etc. where a person can go to escape the stresses of everyday life. 

  • A hole in an animal's den, or through a wall or fence, used for escape or emergency exit; i.e. a hole the animal may bolt through. 

holiday home

noun
  • A second home used for holidays. 

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