grassroots vs people's

grassroots

adj
  • Of, or relating to people or society at the local level, particularly in politics, social movements, etc.; of the grass roots. 

people's

adj
  • Considered to be of, from, or in tune with the common people, rather than from a ruling elite. 

  • In certain socialist states: of, from, or controlled (at least in name) by the common people rather than a ruling elite. 

  • Used other than figuratively or idiomatically: see people, -'s. 

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