There are three kinds of areas: unprogrammed spaces like plazas, sidewalks, and walkways, spaces for programmed activities, and then mixed-traffic areas like alleys.
The unprogrammed spaces are overwhelmingly circulation, but there are some plazas in public areas.
Then, there are programmed spaces, primarily sports facilities.
Finally, there are alleys, which are pretty much a shared space.
And comparing this to all circulation:
So a pretty significant amount of space in a city is dedicated to letting people move around, which isn’t so surprising. I suspect that with appropriate densification, you would see an increase in pedestrian circulation space and a dramatic decrease in parking areas that are clustered along roads away from transit sites.