I see a lot of numbers about 'new single-family houses.' What population do you think is living in a building that fits that description?
According to the 2010 U.S. census, ~80% of the population lives in an urban area, and all projections hold that share to have increased. That's 80+% of the US population that is living in non-single-family buildings, many of which are being remodeled to support greater population density and smaller individual units.