a population's net nutrition - the amount of nutrition people grew up with as compared to biological stress which can cause lower heights in adulthood, stemming from things like food deprivation, hard work, and disease. According to military records of American and European men, Americans were on average two to three inches taller than Europeans. Average heights showed little change until the second quarter of the 19th century, with the Industrial Revolution. The growth of canals, steamboats, and railways, as well as the public school system, mass immigration, and urbanization, increased exposure to diseases. Food prices rose in the 1830s, and industrialization brought along with it growing wealth inequality and business depressions that further worsened the situations of the poor. As a result, average stature and life expectancy declined, and only rebounded from 1910 to 1950, as incomes rose, urban conditions became less crowded, and public health measures were put in place. From the 1930s up until 1980, the average American after-tax income adjusted for inflation tripled, which translated into higher living standards for the American population. Between 1949 and 1969, real median family income grew by 99.3%. From 1946 to 1978, the standard of living for the average family more than doubled. Average family income (in real terms) more than doubled from 1945 up until the 1970s, while unemployment steadily fell until it reached 4% in the 1960s. Between 1949-50 and 1965–66, median family income (in constant 2009 dollars) rose from $25,814 to $43,614, and from 1947 to 1960, consumer spending rose by a full 60%, and for the first time, as noted by Mary P. Ryan, "the majority of Americans would enjoy something called discretionary income, earnings that were secure and substantial enough to permit them to enter sectors of the marketplace that were once reserved for the affluent." In 1960, Americans were, on average, the richest people in the world by a massive margin. During the 1960s, median family incomes increased by over 33%, while per capita expenditures on recreation and meals grew by over 40%. From 1959 to 1969, median family income (in 1984 dollars) increased from $19,300 to $26,700. By 1969, 79.6% of all households owned at least one car, 82.6% owned a refrigerator or freezer, 79% owned a black and white television set, 31.9% owned a color television set, and 70% owned a washing machine. Leisure time also increased. By 1970, it was estimated