Second, in accounting for the contribution of growth in the factor inputs there is a wide variation in the relative weight assigned to the fast-growing capital input versus slow-growing labor. This last issue revolves around the question of how to allocate the incomes of the selfemployed between their own labor effort and the capital that they may bring to the business. Since the total income of the self-employed is nearly equal to that of employees, and exceeded it by a factor of two in the 1970s, the treatment of the mixed income of proprietors is crucial to the derivation of appropriate factor share weights. Somewhat surprisingly, the studies agree that the largest improvements in TFP have occurred in agricultu re, and that TFP growth in services is frequently negative.