manpower vs men

manpower

noun
  • The total number of all available workers; the workforce. 

  • The power exerted by a single person (analogous to horsepower.) 

men

noun
  • enlisted personnel (as opposed to commissioned officers). 

  • (The) people, humanity, man(kind). 

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