in season vs on the market

in season

prep
  • In the time for eating, using, etc. 

  • In heat 

on the market

prep
  • single; not in a committed romantic relationship or otherwise unavailable. 

  • Offered for sale. 

  • During a real estate auction: going to be sold at that auction, i.e. the bid has reached the vendor's reserve. 

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