conceal vs drag up

conceal

verb
  • To hide something from view or from public knowledge, to try to keep something secret. 

drag up

verb
  • Used other than figuratively or idiomatically: see drag, up. 

  • To educate reluctant pupils. 

  • To remind people of something, usually unpleasant, from the past. 

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