discover vs ghostwrite

discover

verb
  • To find or learn something for the first time. 

  • To create by moving a piece out of another piece's line of attack. 

  • To question (a person) as part of discovery in a lawsuit. 

ghostwrite

verb
  • To write under the name of another (especially literary works). 

  • To author a literary work or speech in the place of another. 

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