Lord Provost vs burgomaster

Lord Provost

noun
  • The civic head of certain cities in Scotland, having a role similar to that of mayor. 

burgomaster

noun
  • The mayor, or head magistrate, of a town in the Netherlands, Belgium, Germany and certain other countries. 

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