plug nickel vs two cents

plug nickel

noun
  • A nearly worthless amount. 

two cents

noun
  • A nearly worthless amount, alluding to placing a copper penny on each of the eyelids of a pauper's or slave's body before burial. 

  • One's opinion or thoughts. 

How often have the words plug nickel and two cents occurred in a corpus of books? (source: Google Ngram Viewer )