Some say the tumble is simply numbers. 90% of American homes have a microwave now, as compared to 80% in the 90s.

However, there are other theories, as well.

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"Microwaves have sort of had their day," Howard Telford told Quartz. "As people become more health conscious, and more interested in cooking 'fresh,' that's not helping microwaves," he continued.

Those same people point out while microwaves are sitting in stores, toaster ovens are jumping off shelves at a record rate.

But industry experts point out that built-in microwaves are not seeing the same issue.

They believe the jump in other small appliances is squeezing space on countertops, leading to part of the portable microwave’s troubles. Quartz wonders if this is part of "a slow, drawn-out decline."

More here.