on tap vs on the block

on tap

prep
  • Available directly from the barrel by way of a tap. 

  • Readily available; ready for use in whatever quantity is desired. 

  • On an agenda, planned, expected. 

on the block

prep
  • available at an auction. 

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