erstwhile vs subsequent

erstwhile

adj
  • Former, previous. 

  • Respected, honourable. 

subsequent

adj
  • Following in time; coming or being after something else at any time, indefinitely. 

  • Following in order of place; succeeding. 

  • Following a line in the earth that is more easily eroded. 

noun
  • A subsequent stream or faultline. 

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