The FMHPI provides a measure of typical price inflation for houses within the U.S. Values are calculated monthly but are released at the end of the following quarter. For example, the FMHPI for October, November, and December are published in late February of the following year. Series are available at three levels of geographical aggregation: Metropolitan Statistical Area (MSA), state, and national. All series begin in January, 1975. The national index is defined as a weighted average of the 50 state indexes and Washington, DC. The FMHPI is based on an ever expanding database of loans purchased by either Freddie Mac or Fannie Mae.