interfere vs obstruct

interfere

verb
  • To get involved or involve oneself, causing disturbance. 

  • To sexually molest, especially of a child. 

  • (of waves) To be correlated with each other when overlapped or superposed. 

  • To strike one foot against the opposite foot or ankle in using the legs. 

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. 

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