pay dirt vs recitation

pay dirt

noun
  • A profitable area or period; success. 

  • Earth which contains profitable quantities of ore. 

recitation

noun
  • The act of publicly reciting something previously memorized. 

  • A part of a song's lyrics that is spoken rather than sung. 

  • The material recited. 

  • A regularly scheduled class, in a school, in which discussion occurs of the material covered in a parallel lecture. 

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