"An obvious advantage of a higher family income is that it provides more resources to buy books, computers, high-quality child care, summer camps, private schooling, and other enrichments. Figure 1.6 shows how spending on child-enrichment goods and services jumped for families in the top quintiles to a far greater extent that for those in the bottom income quintiles, as reflected in four large consumer expenditure surveys conducted between the early 1970s and 2005 to 2006."—Whither Opportunity?, p. 11