The National Association of Realtors collects data on existing home sales–including single family homes, condominiums, and co-ops–and publishes them monthly. As released, the data show the seasonally-adjusted annual rate of sales, so as to make comparisons between months and years meaningful. The first chart above shows the seasonally-adjusted annual number of sales by month by region. There are three annual totals, plus monthly figures going back 12 months. The most recent month is a preliminary figure. The second chart shows the number of homes listed for sale (inventory) and the months’ supply of homes. This is calculated based on the current sales velocity, which is the rate at which homes sell.