Irish Traveller vs chav

Irish Traveller

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

chav

noun
  • A working-class youth, especially one associated with aggression, poor education, and a perceived "common" taste in clothing and lifestyle. 

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