handegg vs rugby ball

handegg

noun
  • The ball used to play such a game. 

  • Any of the sports that are called football but are played mainly with the hands and with a prolate spheroid ball; that is, American football and (less often) Canadian and Australian football. 

rugby ball

noun
  • A spheroidal ball designed for the sport of rugby. 

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