amass vs squirrel away

amass

verb
  • To accumulate; to assemble. 

  • to gather a great quantity of; to accumulate. 

  • To collect into a mass or heap. 

squirrel away

verb
  • To stash or hide; to hoard, collect, save, or accumulate; to create a reserve, stash, or hoard of some supply. 

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