Chapel Hill island living

I want to work with others to create a map of Chapel Hill that shows all of the homes that have a pedestrian connection to a food store v those that do not. When I say pedestrian access, I am referring to a space from which automobiles are barred with the exception of crosswalks. So that means sidewalks and trails. Here in Southern Village, ALL of us can reach a grocery store, in fact many of them, including downtown Chapel Hill and other commercial centers such as Eastgate that meet this criterion of pedestrian access. But the res of Chapel Hill. How many homes?