MIAMI (CBSMiami) – Americans are letting a lot of gift cards or other credits go to waste.

A new survey from indicates that there are about $21 billion worth of gift cards, airline voucher and store credits going unused.

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Millennials lead the pack, leaving cards and credits unused at a rate of 55 percent. They are followed by Gen Z and baby boomers.

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Gen X has the lowest rate at 46-percent.

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Sixty-four percent of Americans said they expect to use the cards or credits eventually, but just over a third said they probably won’t.