knock oneself out vs strive

knock oneself out

verb
  • To go ahead; to do as one pleases. 

strive

verb
  • To try to achieve a result; to make strenuous effort; to try earnestly and persistently. 

  • To struggle in opposition; to be in contention or dispute; to contend; to contest. 

  • To vie; to compete as a rival. 

How often have the words knock oneself out and strive occurred in a corpus of books? (source: Google Ngram Viewer )