bother vs knock on wood

bother

verb
  • To do something which is of negligible inconvenience. 

  • To feel care or anxiety; to make or take trouble; to be troublesome. 

  • To annoy, to disturb, to irritate. 

noun
  • Fuss, ado. 

  • Trouble, inconvenience. 

intj
  • A mild expression of annoyance. 

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 bother and knock on wood occurred in a corpus of books? (source: Google Ngram Viewer )