The low point of the current recession occured last April, according to observers who study eight economic indicators which have been reliable guides in the past. This recession cut deeper than the two previous postwar setbacks, but the recovery upturn came faster. Unemployment was aggravated by a greater than usual increase in the working force. Nearly 1 million workers were added to the labor force compared with the usual rate of 0.5 and 0.6 million per year. Average weekly earnings for those working reached record highs.