hammer home vs rehash

hammer home

verb
  • To repeatedly or continually emphasise (an opinion or idea) until or so that a person or group of people understands it. 

rehash

verb
  • To analyze a prior contentious or embarrassing event. 

  • To repeat with minor variation. 

  • To hash (chop food into small pieces) again. 

  • To recompute the structure of a hash table, taking into account any newly added items. 

noun
  • A recomputation of the structure of a hash table, taking into account any newly added items. 

  • Something reworked, or made up from old materials. 

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