sometime vs whilom

sometime

adj
  • Former, erstwhile; at some previous time. 

  • Occasional. 

adv
  • At an indefinite but stated time in the past or future. 

whilom

adj
  • At some time in the past; former, sometime. 

adv
  • At some time in the past; formerly, once upon a time. 

conj
  • During the same time that; while. 

  • Up to the time that; till, until. 

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