plugola vs reward

plugola

noun
  • Undeclared or illicit publicity or product promotion, especially on radio or television. 

reward

noun
  • The result of an action, whether good or bad. 

  • Something of value given in return for an act. 

  • A prize promised for a certain deed or catch 

verb
  • To give a reward to or for. 

  • To recompense. 

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