WASHINGTON (AP) — With college enrollment growing, student debt has stretched to a record number of U.S. households — nearly 1 in 5 — with the biggest burdens falling on the young and poor.

The analysis by the Pew Research Center found that 22.4 million households, or 19 percent, had college debt in 2010. That is double the share in 1989, and up from 15 percent in 2007, just prior to the recession — representing the biggest three-year increase in student debt in more than two decades.

The increase was driven by higher tuition costs as well as rising college enrollment during the economic downturn. The biggest jumps occurred in households at the two extremes of the income distribution. More well-off families are digging deeper into their pockets to pay for costly private colleges, while lower-income people in search of higher-wage jobs are enrolling in community colleges, public universities and other schools as a way to boost their resumes.