day job vs employ

day job

noun
  • One's principal job; one's regular means of income. 

employ

noun
  • The state of being an employee; employment. 

verb
  • To hire (somebody for work or a job). 

  • To use (somebody for a job, or something for a task). 

  • To make busy. 

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