Previously DCLG table 557.
Data up to and including 2002 is from 5% sample. Data from 2003 are based on a significantly enhanced sample size. Data from September 2005are collected via the Regulated Mortgage Survey. 2005 data are based on combined data from the Survey of Mortgage Lenders and the Regulated Mortgage Survey.
Simple averages are more volatile to changes in the structure of the underlying data than mix-adjusted averages.