enroll vs put on the payroll

enroll

verb

To enlist oneself (in something) or become a member (of something)
To enter (a name, etc.) in a register, roll or list
To enlist (someone) or make (someone) a member of

put on the payroll

How often have the words enroll and put on the payroll occurred in a corpus of books? (source: Google Ngram Viewer )