Who is buying Apple products? Old men.

Apple's Eddy Cue shows off new Apple TV
Apple's Eddy Cue shows off new Apple TV

Thank you, grandpa Joe. You're Apple's best customer -- in terms of how much you spend.

Men aged 65 and older spent more on Apple devices than any other demographic group in the United States last year, according to Slice Intelligence, which tracks online shopping data.

That group, though not even one-quarter of all Apple customers, spent $976 online on average per person on iGadgets.

They outspent the young female demographic by more than $400. (Women 25 to 34 spent the least out of all the age groups. See correction below.)

Men far outspent women in every age category by about $200 to $300.

who buys apple products
Men far outspent women.

So what's with older men spending so much on Apple products?

"It's a great feat that [Apple] is appealing across the board," said Jaimee Minney, head of marketing at Slice.

Minney says that the trend is an indication that Apple products are "getting in the hands of people on the late side of the adoption curve," while still remaining very popular with their core customer base -- younger, tech enthusiasts.

There are a few theories about why this is happening.

"Older people might be new to Apple," Minney said. "They haven't bought as much stuff."

Another possible reason: Older customers are buying Apple products to give as gifts.

Here's who's buying what at Apple (AAPL), according to Slice:

-- A higher percentage of customers who buy the iPhone, Macbook Air, Macbook Pro, and Apple TV are between the ages of 25 and 34.

-- Seniors 65 and older, and people between 35 and 44, are the biggest of iPad customers.

-- And those who are 35 to 44 made up the highest percentage of Apple Watch sales.

-- The largest percentage of Apple Music customers are 25- to 34-years-old.

-- Households with an income level between $35,000 and $50,000 spent the least.

-- But, amazingly, households with an income level under $15,000 spent about as much as households with an income level between $125,000 and $150,000.

apple purchases by income

Correction: An earlier version of this story incorrectly stated the percentage of customers who are 65 and older and the age group of women who spent the least on Apple products.

CNNMoney Sponsors