Year-end level from ICI Factbook, table IRA Assets, column Total IRA Assets. Other quarter's levels from ICI unpublished detail. Unadjusted flow is computed as interest and dividends plus net IRA contributions less administrative expenses. Interest, dividends and administrative expenses are computed as a share of total IRA assets based on FOF section estimates. Net IRA contributions is defined as the sum of deductible contributions, nondeductible contributions, rollovers from other plans, Roth contributions and SEP&SIMPLE contributions, less IRA withdrawals. Net IRA contributions are estimated based on data from the SOI Publication 1304 - Individual Income Tax Returns, Table 1.4, row All returns, total, column IRA Payments (deductible contributions), plus column Pension and annuities: Total less Taxable (rollovers), less column Taxable IRA distributions and less an estimate of nontaxable IRA withdrawals (nondeductible and Roth withdrawals) based on earlier annual SOI reports. Nondeductible, SEP&SIMPLE, and Roth contributions are estimated from special studies, such as "Accumulation and Distribution of Individual Retirement Arrangements, 2004" by Victoria L. Bryant, SOI Bulletin: Spring 2008.