pedalo vs roller skate

pedalo

noun
  • A small boat propelled by pedals that directly turn external paddles, used for recreation. 

roller skate

noun
  • A boot having small wheels or casters attached to its sole; used for roller skating. 

verb
  • To skate using roller skates. 

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