on offer vs plentiful

on offer

prep
  • For sale at a reduced price. 

  • Available to take; at hand; being offered or to be offered. 

plentiful

adj
  • Existing in large number or ample amount. 

  • Yielding abundance; fruitful. 

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