hassle vs pick at

hassle

verb
  • To trouble, to bother, to annoy. 

  • To engage in a mock dogfight. 

  • To pick a fight or start an argument with. 

noun
  • Trouble, bother, unwanted annoyances or problems. 

  • A fight or argument. 

  • An action which is not worth the difficulty involved. 

adj
  • hassling; hasslesome 

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 hassle and pick at occurred in a corpus of books? (source: Google Ngram Viewer )