dampness vs water vapor

dampness

noun
  • Moderate humidity; moisture; moistness; the state or quality of being damp. 

  • The degree to which something is damp or moist. 

water vapor

noun
  • Water in a gaseous state, especially when diffused in the atmosphere. 

  • Steam. 

How often have the words dampness and water vapor occurred in a corpus of books? (source: Google Ngram Viewer )