When many women were forced to enter the workforce during World War I, they could no longer dedicate as much time to domestic labor, including the purchasing and preparing of food. Refrigerators were introduced during the interwar period as a solution to this problem; they kept perishables fresher for longer and therefore reduced the number of trips to the market. Early domestic refrigerators were prohibitively expensive (both to purchase and to power) and were associated with the upper classes, often advertised with images showing a maid using them or filled with extravagant items like champagne. This dramatically changed, however, with the advent of the EDF and the standardization of appliances. In 1954, only around 6.7 percent of all French households had refrigerators. By 1962, that number had risen to 40.3 percent; by 1970, it was 90 percent.