Henceforth 2015 will be remembered as the year that we colored.
Last year, the adult coloring book genre exploded in popularity: Titles like Johanna Basford’s Enchanted Forest and Lost Ocean and Blue Star’s “stress relieving” coloring set dominated book sales.
Three of Amazon’s 10 best-selling books in 2015 were coloring titles for grown-ups; a new round-up from industry publication Publishers Weekly shows a similar outcome. As recently as last summer, coloring books made up 17% of book sales in Brazil.
Google Trends show that curiosity around coloring has grown considerably in the last year:
Dozens of new titles are slated for release early this year, and publishers and book-sellers don’t see the trend slowing down.
“We thought people would stop caring by now, but it has longevity,” Gabrieli Coeli tells Quartz. Coeli is chief creative officer of Blue Star Coloring, a collective of illustrators established in 2015 which produced some of the year’s run-away hits.
“The appeal for coloring books extends past traditional publishing products,” he says. “They’re self-care products.”
Universities, libraries, and senior citizen centers are catching wind and holding coloring book parties. In November, Barnes and Noble locations across the US held coloring activities for “stressed out America.” And book stores are adding new sections for adult coloring.
One thing that sets coloring books apart is that they can’t be reused or borrowed—once you’re done, that’s it. Longtime publishing consultant Mike Shatzkin writes in an email to Quartz that this is a big reason to believe the purchasing trend will continue. “As long as they’re needed, they’ll be bought,” he writes.
In the future, coloring book fans can expect publishers to experiment with themes: At New York City’s iconic Strand Bookstore, a Harry Potter coloring book and one by Abbi Jacobson of the popular show Broad City have both proved popular, in addition to the usual shapes and flower designs.
Publishers can expect new audiences as well, like men who want coloring books geared toward them.
Though there isn’t yet much research to support a therapeutic effect of coloring, the activity seems to resonate with the stressed out set because of its calming, meditative, and screen-free nature. And as neuroscientist and science writer Jordan Gaines Lewis writes, creation for its own sake—rather than as a means of productivity—seems to appeal to the overworked.
All this growth could eventually be problematic for publishers, says Shatzkin, if sales can’t keep up with the sheer number of new titles. But for now, at least, it seems adult coloring books are here to stay.