illustrate vs stencil

illustrate

verb
  • To provide a book or other publication with pictures, diagrams or other explanatory or decorative features. 

  • To clarify something by giving, or serving as, an example or a comparison. 

stencil

verb
  • To print with a stencil. 

noun
  • A two-ply master sheet for use with a mimeograph. 

  • A thin sheet, either perforated or using some other technique, with which a pattern may be produced upon a surface; a utensil that contains a perforated sheet. 

  • A pattern produced using such a utensil. 

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