It is generally the ratio of median house prices to median familial disposable incomes, expressed as a percentage or as years of income. It is sometimes compiled separately for first-time buyers and termed attainability.[citation needed] This ratio, applied to individuals, is a basic component of mortgage lending decisions.[citation needed] According to a back-of-the-envelope calculation by Goldman Sachs, a comparison of median home prices to median household income suggests that U.S. housing in 2005 was overvalued by 10%. "However, this estimate is based on an average mortgage rate of about 6%, and we expect rates to rise", the firm's economics team wrote in a recent[when?] report.[10] According to Goldman's figures, a one-percentage-point rise in mortgage rates would reduce the fair value of home prices by 8%.[citation needed] The deposit to income ratio is the minimum required downpayment for a typical mortgage [specify], expressed in months or years of income.