hobby vs rocking horse

hobby

noun
  • An extinct breed of horse native to the British Isles, also known as the Irish Hobby 

  • An activity that one enjoys doing in one's spare time. 

  • Any of four species of small falcons in the genus Falco, especially Falco subbuteo. 

rocking horse

noun
  • a child’s toy consisting of a (usually wooden) horse mounted on a rocker or swing 

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