consult vs rack brains

consult

verb
  • To seek the opinion or advice of another; to take counsel; to deliberate together; to confer. 

  • To advise or offer expertise. 

  • To ask advice of; to seek the opinion of (a person) 

  • To have reference to, in judging or acting; to have regard to; to consider; as, to consult one's wishes. 

  • To refer to (something) for information. 

  • To work as a consultant or contractor rather than as a full-time employee of a firm. 

noun
  • A visit, e.g. to a doctor; a consultation. 

rack brains

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