front door vs revolving door

front door

noun
  • The door at the main entrance to a building or house, normally fronts onto a street. 

  • The path of a pitch which starts inside and then slides over the plate. 

  • The normal portal page to a website. 

  • vagina or penis, as a means of sexual intercourse, contrasted with the anus or "back door" 

  • The entire main entrance to a building or house. 

  • The habitual or designated main entrance to a room that has more than one door. 

revolving door

noun
  • A door that rotates around a central pivot. 

  • A movement of personnel between roles as legislators and regulators, on the one hand, and members of the industries affected by the legislation and regulation, on the other. 

  • A system or institution in which people exit and immediately reenter. 

  • Synonym of recidivism 

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