count on vs knock on wood

count on

verb

  • To rely on, trust, or expect. 

knock on wood

verb

  • To take a customary action to ward off some misfortune that is believed to be attracted by a presumptuous statement. 

intj

  • Hopefully; a self-directive to undertake the customary action to ward off bad luck. 

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