Are the Kardashians struggling to keep up their popularity?

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Family flop: Cosmopolitan's cover featuring the Kardashian-Jenner women was one of its worst sellers of the year, selling nearly 100,000 copies less than average

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Audience rejection: Kylie Jenner's solo February cover didn't fare much better, selling 35,654 newsstand copies less than average

Is the whole world finally suffering from Kardashian fatigue? Well, not exactly - but enough people are over the famous family to make them some of the worst-selling magazine cover stars in 2015.

Though they's still proven to be moneymakers in other arenas - their apps made millions of dollars this year - when it comes to the publishing world, the Kardashian-Jenner clan no longer inspire spending.

According to WWD, several major magazines saw their monthly circulation fall with one or more of the reality stars on their covers, with Cosmopolitan seeing an 18 per cent drop in single-copy sale when all six women graced its cover in November.

Whoops: Glamour put Kim Kardashian on it's July cover and saw a whopping 14.6 per cent drop from its first-half sales average

Though the celebrities who pose on the covers on magazines don't effect monthly subscription rates, they can have a major impact on single-copy sales. 

For the first half of 2015, for example, Cosmopolitan's single-copy sales averaged about 531,086 copies. However its 'First Family' issue - which featured Kim, Kourtney, Khloe, Kendall, Kylie, and Kris on the cover - sold only 436,500 copies.

Kylie Jenner's solo cover in February also hurt that first-half-of-the-year average, as the 18-year-old's issue sold just 495,423 copies.

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A quick peek: When Kendall Jenner covered GQ in May, the photos got a lot of buzz online - but the issue sold 10,000 copies less than usual

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Beauty queen? Despite the fact that many now call her a supermodel, Kendall's Allure cover also sold 4,000 copies less than average

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Winner: The girls' dad, Caitlyn Jenner, was the biggest success story, giving Vanity Fair a 264 per cent sales bump when she debuted the first image of herself as a woman

Though that's less than the combined average of other cover stars Cameron Diaz, Gwen Stefani, Hilary Duff, Madonna, and Zoey Deschanel, it is, actually, more than what was sold by her family's group cover.

But the Comso covers weren't the only flops. 

Glamour put Kim on it's July cover and saw a 14.6 per cent drop from its first-half sales average. 

And despite her supermodel status, Kendall didn't fare much better, with her May GQ cover selling about 10,000 copies less that its first-half average. Her Allure cover in March did slightly better, selling only about 4,000 copies less than average.

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Busty boost: Kim's Rolling Stone cover did quite well, too, with 89,100 single copies sold - but that paled in comparison to Caitlyn's newsstand sales

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About the same: Though Kylie's Teen Vogue cover offered a bigger boost in sales than her Cosmo one, it only sold 1,000 copies above average