extrude vs protrude

extrude

verb
  • To push or thrust out. 

  • To expel; to drive off. 

  • To form or shape (a metal, plastic etc.) by forcing it through a die or an opening. 

protrude

verb
  • To thrust out, as through a narrow orifice or from confinement; to cause to come forth. 

  • To extend from, above or beyond a surface or boundary; to bulge outward; to stick out. 

  • To cause to extend from a surface or boundary; to cause to stick out. 

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