The just-released Statistics of Income Bulletin (Summer 2004) includes Sole Proprietorship Returns, 2002, by Kevin Pierce (SOI) & Michael Parisi (SOI). Here is the opening:

Nonfarm sole proprietorship profits increased 1.7% for Tax Year 2002 to $221.1 billion. While a majority of the principal sole proprietorship industrial sectors reported increased profits, a few sectors reported a decrease in profits. The largest percentage increase in profits for a major industrial sector was 13.7% for wholesale trade. The next largest percentage growth in profits for a major industrial sector was 12.9% for finance and insurance, followed by a 10.6% growth reported by real estate and rental and leasing. Four major industrial sectors showed a decline in profits for 2002. The largest percentage decrease in profits was in retail trade, with a 20.8% decrease, followed by transportation and warehousing with a 5.4% decrease.