At the end of the 1960s, total wages and salaries accounted for close to 60 percent of the income received from all sources in the United States. Since then, the share of total national income has trended downward. Today only 51 percent of total national income is derived from wages and salaries. Some media pundits and politicians have claimed that the decline in the percentage of national income going to wages and salaries is evidence that workers are receiving a smaller share of national income. However, the total compensation received by workers, which includes employer-paid health insurance and pension benefits, has remained close to 70 percent of the national income since the 1940s. Effectively, workers have exchanged some of their wage and salary payments for other, usually nontaxable, benefits. This illustrates why it is important to include all income receipts when measuring the distribution of income.

If the percentage of the population made up of workers who receive wages and salaries has remained the same since the 1960s, has a Lorenz curve based only on U.S. income from wages and salaries necessarily become more bowed out over time?