knock on wood vs rely

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. 

rely

verb

  • to trust; to have confidence in; to depend. 

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