lady of leisure vs streetwalker

lady of leisure

noun
  • A female prostitute. 

  • An unemployed woman or one who has retired from work. 

  • A lady who is of independent means and so does not need employment; one who is free from duties and responsibilities. 

streetwalker

noun
  • A prostitute who looks for customers on the streets and in other public places. 

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