Credit card use in the U.S. has dropped drastically over the past year.

TransUnion, a credit reporting agency, found that more than 8 million Americans have stopped using their credit cards, an 11 percent decline.

A small percentage of those people are no longer using their cards, because banks have cut them off for getting behind on payments. However, most people have just stopped using them.

"One can quite reasonably infer that's not voluntary," said Ezra Becker, vice president of research and consulting in TransUnion's financial services business unit.

"They're simply either not purchasing as much or paying down balances," he added.

Many have switched to using debit cards. The use of debit cards has increased steadily and even surpasses credit card use in both the number of transactions and dollar volume.