interplay vs tit for tat

interplay

noun

  • Interaction; reciprocal relationship. 

verb

  • To interact. 

tit for tat

noun

  • Equivalent retribution; an act of returning exactly what one gets; an eye for an eye. 

  • A hat. 

How often have the words interplay and tit for tat occurred in a corpus of books? (source: Google Ngram Viewer )