back o' Bourke vs bumfuck middle of nowhere

back o' Bourke

adv

  • At or to an extremely remote place. 

name

  • An extremely remote place. 

bumfuck middle of nowhere

noun

  • Synonym of bumfuck nowhere 

How often have the words back o' Bourke and bumfuck middle of nowhere occurred in a corpus of books? (source: Google Ngram Viewer )