convenience vs sweeten the pot

convenience

verb
  • To make convenient 

noun
  • Any object that makes life more convenient; a helpful item. 

  • The quality of being convenient. 

  • A convenient time. 

sweeten the pot

verb
  • To make something more desirable. 

  • To increase a wager. 

How often have the words convenience and sweeten the pot occurred in a corpus of books? (source: Google Ngram Viewer )