bebop vs heavy metal

bebop

noun
  • An early form of modern jazz played by small groups and featuring driving rhythms and complex, often dissonant harmonies. 

verb
  • To participate in bebop jazz, such as by dancing in a way associated with the genre. 

  • To walk in an easygoing, carefree manner. 

heavy metal

noun
  • A genre descended from rock music, characterized by massive sound, highly amplified distortion, and overall loudness, often with extended guitar solos, and lyrics that involve aggressive or fantastic imagery. 

  • Any metal that has a specific gravity greater than about 5, especially one, such as lead, that is poisonous and may be a hazard in the environment. (There are many different definitions of what counts as a heavy metal; see Heavy metals for a discussion.) 

  • Great influence or power. 

  • guns or shot of large size. 

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