excoriate vs pick at

excoriate

verb
  • To strongly denounce or censure. 

  • To wear off the skin of; to chafe or flay. 

pick at

verb
  • To pick on or repeatedly criticize (someone). 

  • To touch, grab, handle, or pull tentatively or gingerly, using a utensil or one's fingers. 

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