floor-through vs vacancy

floor-through

noun
  • An apartment which covers the entire depth of a building. 

vacancy

noun
  • An available room in a hotel; guest house, etc. 

  • Empty space. 

  • An unoccupied position or job. 

  • Lack of intelligence or understanding. 

  • A blank mind, unoccupied with thought. 

  • A defect in a crystal caused by the absence of an atom in a lattice 

How often have the words floor-through and vacancy occurred in a corpus of books? (source: Google Ngram Viewer )