myriad vs numerousness

myriad

noun
  • A countless number or multitude (of specified things) 

  • Ten thousand; 10,000 

adj
  • Great in number; innumerable, multitudinous 

  • Multifaceted, having innumerable elements 

numerousness

noun
  • The state or quality of being numerous. 

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