obstruct vs set back

obstruct

verb
  • To impede, retard, or interfere with; hinder. 

  • To get in the way of so as to hide from sight. 

  • To block or fill (a passage) with obstacles or an obstacle. See synonyms at block. 

set back

verb
  • To delay or obstruct. 

  • To remove from or allow distance. 

  • To install or position behind a boundary or surface, or in a recess. 

  • To cost money. 

  • To reverse, go backwards. 

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