on tap vs vouchsafed to someone

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. 

vouchsafed to someone

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