solarium vs sunroom

solarium

noun
  • A room, rooftop, balcony, or terrace, used for its abundant sunlight (especially) when used as a medical treatment. 

  • Synonym of tanning salon, a room or business used for its sunlamps or tanning beds. 

sunroom

noun
  • A room used for its abundant sunlight, especially one in a residence with numerous large glass windows. 

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