from day to day vs per diem

from day to day

adv

  • focusing on one day at a time. 

  • daily. 

per diem

adj

  • per day; daily. 

noun

  • A daily stipend. 

  • A daily allowable limit for expendables. 

How often have the words from day to day and per diem occurred in a corpus of books? (source: Google Ngram Viewer )