available vs on offer

available

adj
  • Valid. 

  • Free to meet someone, speak on the telephone, enter a romantic relationship, or the like. 

  • Readily obtainable. 

  • Such as one may avail oneself of; capable of being used for the accomplishment of a purpose. 

on offer

prep
  • For sale at a reduced price. 

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

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