guardianship vs promotion

guardianship

noun
  • The office or position of one acting as a guardian or conservator, especially in a legal capacity. 

promotion

noun
  • An advancement in rank or position. 

  • An event intended to increase the reach or image of a product or brand. 

  • Transformation of a pawn into a piece (by reaching the opponent's back rank). 

  • Dissemination of information in order to increase its popularity. 

  • Forward motion. (Contrast remotion.) 

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