Stock figures used to estimate the average for each county, region and the nation are taken at 1 April of the following financial year. Average rents data for between 2003-04 and 2007-08 inclusively are estimated using total stock figures from Housing Revenue Account (HRA) audited base claim form. For 2008-09, stock figures for local authorities (LAs) where administrative boundaries changed on 1 April 2009 are taken from the HRA 2nd advance subsidy form as at 1 April 2010. Ordinarily stock figures would be taken from the HRA audited base claim form, however these figures were collected on the LA boundaries post 1 April 2009 and could not be reconciled with rents figures for 2008/09, which were collected on LA boundaries pre April 2009. Average rents data for 2003-04 and onwards are based on a standardised 52 week collection calculated by CLG from figures provided by local authorities.