Private investment in residential construction declined from 12.7 percent of annual investment in 1960 to 6.5 percent in 1970 but rose to 7.2 percent in 1971. In absolute terms private investment increased from about 174 million leva to 262 million leva. By 1973, however, new restrictions were being introduced on housing construction by private individuals. As much as 90 percent of the residential construction in 1960 and 70 percent in 1971 was privately financed. In the 1968-70 period about half the private investment in housing was supported by bank loans or by loans from special funds of employing organizations. The rise in the volume of capital per worker in the 1960-70 period as a result of the investment activity did not produce a corresponding increase in labor productivity; that is, the efficiency of investment declined. Whereas the amount of fixed capital per worker in the sphere of material production increased at an average annual rate of 10.4 percent, and the volume of machinery and inventories rose by 12.5 percent per year, output per worker increased at an annual rate of only 7.7 percent. In an effort to increase the efficiency of investment, the Tenth Party Congress, convened in the spring of 1971, directed that 35 percent of new investment in the sphere of material production during the 1971-75 period should be used for the reconstruction and modernization of existing facilities. In 1972, however, the proportion of investment used for this purpose was only 18 percent. In the context of the eventually abandoned program for economic decentralization, provision was made for reducing the role of the central government budget in financing investments and for increasing participation by investors with their own funds and bank credits. In the sphere of material production, excluding trade, budgetary allocations in 1965 accounted for 55 percent of investment, and bank credits made up 7 percent; in 1969 investment funds from these sources constituted 21 and 32 percent, respectively. The contribution from the budget, however, rose again after 1969 to 28 percent in 1971, whereas bank credits declined to less than 20 percent of the investment funds. The share of investors' own resources, including funds of local governments, increased from 36 percent in 1965 to 52 percent in 1971. Budgetary investment funds are being increasingly concentrated on projects in the fields of services and raw materials production.