Crop cultivation has slowly become less important in the gross output of the agricultural sector. Cropping and livestock were almost equal branches in 1960, but by 1985 crops accounted for only 43% of gross agricultural output compared with 57% for livestock products. Main crop products in the 1980s were wheat, barley, potatoes, sugar beets, rye, and hops (an important export crop). Sugar, derived from sugar beet production, is both a significant export crop (especially to hard currency areas) and an important item of domestic consumption. Fruit and vegetables accounted for only a small part of the cultivated area. Since the 1950s, the supply of livestock has gradually increased because of government encouragement. Producers have been urged to meet the demand for meat that accompanied the rise in income levels of the population. After the collectivization of agriculture, raising livestock increasingly became a large-scale operation, usually undertaken in conjunction with cropping. The major constraint to livestock expansion has been a shortage of fodder and feed mixtures, although government pricing policies and the labor demands of animal husbandry have also tended to deter efforts. During the 1970s, progress was made in expanding the supplies of fodder and feed mixtures and the country's processing capacity. However, it remained necessary to supplement the supply of feed and fodder through imports, which became increasingly burdensome because they came from noncommunist countries and thus required payment in convertible currencies.