doorstep vs revolving door

doorstep

noun
  • An outside step leading up to the door of a building, usually a home. 

  • One's immediate neighbourhood or locality. 

  • A thick slice, especially of bread. 

verb
  • To visit one household after another to solicit sales, charitable donations, political support, etc. 

  • To corner somebody for an unexpected interview. 

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 doorstep and revolving door occurred in a corpus of books? (source: Google Ngram Viewer )