Whitman's sampler vs medley

Whitman's sampler

noun
  • A diverse collection. 

medley

noun
  • A collection or mixture of miscellaneous things. 

  • A competitive swimming event that combines the four strokes of butterfly, backstroke, breaststroke, and freestyle. 

  • A cloth of mixed colours. 

  • A collection of related songs played or mixed together as a single piece. 

verb
  • To combine, to form a medley. 

How often have the words Whitman's sampler and medley occurred in a corpus of books? (source: Google Ngram Viewer )