Year-end level from SOI Bulletin, annual article on Partnership Returns, table Balance Sheet, by Profit Status and Selected Industrial Group, line U.S. government obligations (total for all industries except Agriculture, forestry, fishing and hunting, and Finance and insurance). Year-end level also includes FOF estimate for U.S. government securities held by sole proprietorships calculated as the ratio of security holdings to income from the FRB 2003 Survey of Small Business Finance multiplied by the year-end level from SOI Bulletin, annual article on Nonfarm Sole Proprietorships, table Income Statements, by Industrial Sectors, line Business receipts, total (total for all industries except Agriculture, forestry, fishing and hunting, and Finance and insurance). Series is converted to quarterly by linear interpolation. The proportion of Treasury securities to bank loans n.e.c. and mortgage liabilities calculated from the latest SOI date is used to estimate data for quarters going forward. Unadjusted flow is the change in the level; data for the most recent ten years show no significant seasonality.