Last year, the five major players of the PC industry—Dell, Microsoft, Lenovo, Intel, and Hewlett-Packard—joined forces on an ad campaign to promote the advantages of desktop computers. It was nothing short of cringe-worthy.

The tagline “PC Does What?” was an attempt at millennial speak, but ended up as unintentional irony since people do, indeed, seem to be asking what a PC does that a smartphone doesn’t.

Earlier this month, comScore, a media analytics company, released its annual report on cross-platform media usage. It didn’t look good for PCs (i.e., desktops and laptops).

Amazingly, desktop usage didn’t just drop from last year—it also fell below 2013 levels of usage. Tablet usage shrunk as well while smartphone usage continued to balloon, jumping 31 percent from 2013 to 2014 and 17 percent from 2014 to 2015. In total, smartphone usage represents 54 percent of the total pool of time spent here. Desktop, meanwhile, accounts for 35 percent of time spent with digital media.

That mark aligns with eMarketer’s most recent projections, which looked at total time spent in terms of hours and minutes.

As you can see in this graph below, mobile has exploded in the past few years while desktop has stagnated.

But that doesn’t mean that mobile will continue to boom. eMarketer has mobile growth slowing down considerably, particularly after this year, in North America and Europe. Mobile still has a bit more room to grow globally, though not nearly at the levels of the early 2010s.

Naturally, the change in behavior has affected the ad world. Mobile makes up 26 percent of time spent with media and constitutes 24 percent of ad spend. Desktop—which, according to eMarketer, makes up 22 percent of the total time spent—only constitutes 14 percent of ad spend. It’s possible that media buyers overcorrected for mobile, though desktop-specific problems like adblocking and fraud may also contribute to lower spend. Meanwhile, print continues to command a disproportional amount of spend, perhaps because of high-value customers or simply from inertia.

Time spent is either stagnating or decreasing for every type of media besides mobile. Facebook, Snapchat, and Apple are all pushing people to spend more time on mobile, and it makes sense that a computer you can take anywhere will dominate the future of digital. Other forms of media—like desktop—will certainly stick around, but mark down 2015 as the year that mobile stuck the knife through the heart of desktop.