Many millennials are in the red.

More than half (51.5%) of those in a new survey from Insider and Morning Consult said they had credit-card debt. The survey polled 2,096 Americans about their financial health, debt, and earnings for a new series, "The State of Our Money." More than 670 respondents were millennials, defined as ages 23 to 38 in 2019.

Of those who were in credit-card debt, slightly more than half (54%) said they owed less than $5,000, and 24% said they owed $5,000 to $10,000. The remaining one-fourth said they owed significantly more — 9% owe $10,000 to $20,000, 4.5% owe $20,000 to $30,000, and 4.5% owe more than $30,000.

And it's stressing them all out. About 67% of the millennial respondents with credit-card debt said they had a lot or some stress about it — even those with smaller sums of debt. About 55% of those $5,000 in debt were stressed about it, compared with 82% of those $5,000 to $10,000 in the hole and 84% of those $10,000 to $20,000 in the hole.

Read more: Millennials and Gen X are both stressed, broke, and in debt — but Gen X is more worried about it

Living costs are outpacing income growth for millennials

These indebted millennial respondents reflect some of the financial woes facing their generation as a whole, particularly when it comes to an increasing cost of living that outpaces their income growth.

Multiple studies show that millennials have less purchasing power than previous generations did at the same age. A 2018 report from Student Loan Hero that found that rent, home prices, and college tuition had all increased faster than incomes in the US.

It doesn't help that those ages 25 to 34 on average have seen incomes increase by just $29 since 1974 when adjusted for inflation, according to a recent SuperMoney report that analyzed US Census Bureau data. That year, they were earning an average of $35,426. By 2017, that rose to a mere $35,455.

That's way less than the inflation-adjusted income growth for other age groups — $2,900 for adults ages 35 to 44 and nearly $5,400 for those ages 45 to 54 in the same time period.

When most of a minimal income ends up on rising housing and education costs, it's easy to end up putting daily living costs on a credit card.