hot jazz vs ragtime

hot jazz

noun
  • Synonym of Dixieland (“jazz music subgenre”) 

ragtime

noun
  • A piece of music in this style. 

  • A musical form having a rhythm characterized by strong syncopation in the melody with a regularly accented accompaniment. 

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