grassroots vs societal

grassroots

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

societal

adj
  • Of or pertaining to society or social groups, or to their activities, customs, etc. 

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