From July 1947 To May 1952, Percentage Shown Is For "Volume And Profit" Combined. From October 1952, It Is For Profit Alone. The Data Represent The Percentage Reporting Higher Profit, Plus Half Of The Percentage Reporting "No Change." Source: Purchasing Agents Association Of Chicago: Combined Statistical And Analytical Report Of The Business Survey Committee, Monthly Issues.
This NBER data series m09102 appears on the NBER website in Chapter 9 at http://www.nber.org/databases/macrohistory/contents/chapter09.html.
NBER Indicator: m09102
Release: NBER Macrohistory Database
National Bureau of Economic Research, Profit, Percentage Reporting Higher Profit for United States [M09102USM156NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M09102USM156NNBR/, August 2, 2015.