Jock vs copilot

Jock

noun

  • A Scot. 

name

  • A nickname. 

  • A given name. 

  • A surname. 

copilot

noun

  • A backup or assistant pilot of an aircraft. 

verb

  • To serve as relief or assistant pilot. 

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