A new Gallup poll reinforces what some critics have been saying about the nation’s current health care system: health insurance varies widely across income groups, with those of lower means most likely to lack health coverage.

The poll revealed that Americans in their mid-twenties are the most likely to be uninsured and that insurance coverage correlated with income. For example, only 44 percent of 35-year-olds making less than $24,000 per year had health insurance versus 100 percent of septuagenarians earning more than $24,000.

In 2009, Gallup found that overall 16.2 percent of respondents lacked health coverage, a slight increase over 2008, the first year that Gallup collected data on health coverage. These uninsured, however, are not randomly distributed among the populace but are grouped according to age and income.

The youngest interview group, 18-year-olds, had a relatively high insurance rate of 84 percent, apparently reflecting their status as dependents covered by their parents’ policies. Coverage then abruptly drops to the lowest level of 66 percent by age 22, rising slowly until age 65, when Medicare becomes available.

It is interesting to note that even after age 65, when most Americans become eligible for Medicare, respondents with the highest incomes are still more likely to report health insurance coverage than those with the lowest.