employ vs line of work

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. 

line of work

noun
  • an occupation 

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