bro vs cobber

bro

noun
  • brother (usually used to address a male) 

  • fratboy (or someone that espouses the fraternity bro culture) 

  • brother (a male comrade or friend; one who shares one’s ideals) 

  • brother (a male sibling) 

pron
  • he or him 

cobber

noun
  • A pal, buddy, mate, friend; often used in direct address by one male to another. 

  • A sweet consisting of a small block of hard caramel covered in chocolate. 

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