overstrain vs vex

overstrain

verb
  • To subject to an excessive demand on strength, resources, abilities, or the imagination. 

noun
  • excessive strain 

vex

verb
  • To cause (mental) suffering to; to distress. 

  • To toss back and forth; to agitate; to disquiet. 

  • To twist, to weave. 

  • To annoy, irritate. 

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