reconstruct vs regrade

reconstruct

verb
  • To construct again; to restore. 

  • To attempt to understand an event by recreating or talking through the circumstances. 

regrade

verb
  • To regroup or reassign. 

  • To change the classification of (potentially secret documentation). 

  • To grade again, give a new grade or grading to. 

noun
  • The act or process of grading again. 

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