lithograph vs xylograph

lithograph

noun
  • A printed image produced by lithography. 

verb
  • To create a copy of an image through lithography. 

xylograph

noun
  • A print taken from such an engraving. 

  • An engraving in wood or woodcut, especially one used in printing predating the Western tradition (14th c.). 

verb
  • To make a print from an engraving in wood. 

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