Irish Traveller vs itinerant

Irish Traveller

noun
  • A member of a particular nomadic ethnic minority in Ireland, the Pavee. 

itinerant

noun
  • A member of the Travelling Community, whether settled or not. 

  • One who travels from place to place. 

adj
  • Habitually travelling from place to place. 

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