From Goldman Sachs, a very useful chart.
The diagram below breaks down the US housing market into several categories (all figures refer to 2010 and come from the American Community Survey and the NAR). Housing units can be either occupied or vacant, and occupied units are either currently listed for sale or unlisted/not for sale. Vacant units can be listed for sale, seasonal or recreational properties that are not for sale, or can fall into a number of other categories (e.g. for rent, sold but not yet occupied, or “held off market”).
Photo: Goldman Sachs