cable tray vs fistula

cable tray

noun
  • A rigid structure to support electric cables; a type of raceway, normally having the appearance of a ladder and open at the top to facilitate changes. 

fistula

noun
  • A tube, a pipe, or a hole. 

  • An abnormal connection or passageway between organs or vessels that normally do not connect. 

  • The tube through which the wine of the Eucharist was once sucked from the chalice in certain ceremonies (such as papal Masses). 

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