The Commonwealth Fund is out today with a new report on the economic disparities that underlie gaps in insurance coverage in the United States. It finds that the majority of “low-income” families — those making less than $29,726, or 133 percent of the Federal Poverty Line, spent some time uninsured in the past year. That figure drops to 12 percent among those earning $89,400, or 400 percent of FPL.

This underscores how central the health reform law’s expansion of Medicaid — in which anyone below 133 percent of the poverty line qualifies for the program — will be to the law’s expanded coverage. Everyone represented by the yellow triangles above becomes eligible for Medicaid in 2014. While the private insurance expansion could get thrown into limbo by the Supreme Court, there’s pretty widespread agreement that, absent full repeal of the bill, health reform’s Medicaid expansion is not going anywhere. And that means a wide-reaching expansion of the entitlement program about two years from now.