If paying for child care has come to feel for many American families like putting a child through college, there’s a reason for that.

The average annual cost of full-time, center-based child care in the United States now exceeds the average annual cost of in-state tuition, according to a “Care Index” released Tuesday by New America, a think tank in Washington, D.C. That amount, of $9,589 per child, represents nearly a fifth of annual median household income and 85 percent of the yearly median cost of rent.

Despite the high costs, day-care workers are paid poverty wages, turnover is high, and only a small percentage of centers are nationally accredited, a marker of quality.

“The short version,” the report said, “is that the early care and learning system isn’t working. For anyone.”

The report represents one of the most comprehensive looks to date on the patchwork system of in-home and center-based care relied on by families of more than 12 million American children under the age of 5.

No single state in the country had a system of care that scored well in each of three key areas of affordability, accessibility and quality, the report said.

“Even in the best states, we still unearthed a really broken system,” said Brigid Schulte, director of New America’s Better Life Lab and lead author of the report.

The index aims to inform a national conversation about early care and learning that the country is beginning to undertake after decades of inaction amid rapidly changing family dynamics.

The leading presidential candidates have presented plans for reforming child-care policies, particularly aimed at making care more affordable. Among other proposals, Donald Trump’s plan would let parents deduct child-care expenses from their income taxes, up to an amount equivalent to the average cost of care in their state. Hillary Clinton has said she would reform the system so that no family spends more than 10 percent of household income on child care.

The Care Index draws on data from government and other sources, and includes previously unpublished proprietary data from Care.com, a job-matching website for in-home caregivers.

The new data show that the average cost for in-home full-time care is $28,353 a year, or more than half the U.S. median income. The costs for a full-time nanny range from $25,774 a year in Wisconsin to $33,366 in Washington, D.C.

To measure quality, the index used accreditation ratings from two major national organizations — the National Association for the Education of Young Children and the National Association for Family Child Care. The portion of accredited child-care centers ranged from a low of 1 percent in South Dakota to a high of 46 percent in Connecticut. In Washington, D.C., 56 percent are accredited.

The report did not issue a ranking for all 50 states but put them into performance quartiles.

Massachusetts was in the highest quartile, yet the cost of full-time care was very high — $13,208 per year — almost equal to the average cost of rent in the state. Still, caregivers earned paltry salaries. The report profiled one preschool teacher with three decades of experience who was earning $25,000 a year and living on food stamps.

Georgia, one of the nation’s leaders in investing in universal pre-kindergarten, was rated above average overall, but there, too, high-quality programs for infants and toddlers were scarce. A state report in 2009 found that 70 percent of all licensed infant and toddler classrooms were rated as low quality, with children in environments “inadequate for their health and safety” that “do not promote their cognitive and social-emotional development.” One mother featured in the report started paying for child care before her baby was born, just to reserve a spot in a quality program.

The last time the federal government attempted to overhaul child care was in 1971, when both houses of Congress passed a bipartisan law for universal quality child care that would be available to everyone on a sliding scale.

But President Richard Nixon vetoed the bill, writing that there needed to be “a great national debate” before the government adopted a “communal approach” to child-rearing and moved away from a “family-centered approach,” the report said.

Since then, family life in America has utterly changed. Nearly two-thirds of children under 6 have both parents in the workforce, compared with 28 percent of children in 1970. The number of single-parent headed families has also grown.

“The world has changed,” Schulte said. “The time for that debate is now.”