Someday, we may launch an index that attempts to describe how shareable your city is. How many CSAs? How much free wifi? How "smart" is the power grid? How many miles of bike lanes? And so on.
One of the key questions the index would have to answer: How many people share transportation to work? This graph answers that question--and it's instructive to compare it to "Dangerous By Design," which ranks pedestrian safety in 360 cities.