The Freddie Mac House Price Index (FMHPISM) provides a measure of typical price inflation for houses within the United States. Values are calculated monthly and 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 states and Washington, D.C. indices. The FMHPI is based on an ever expanding database of loans purchased by either Freddie Mac or Fannie Mae.