Credit: comScore Media Metrix Multi-Platform & Mobile Metrix, U.S., Dec 2015 vs. Dec 2014 vs. Dec 2013

It’s common knowledge that digital media has seen explosive growth, but an interesting picture emerges when you look at just where the increased consumption has come from.

The numbers, as laid out in a new report from comScore, read like a funeral dirge for desktop.

According to the report, total usage of digital media has nearly tripled since 2010 and is up more than 30 percent since 2013. But the distribution of that growth is hugely skewed.

The report said smartphones alone have contributed to more than 90 percent of the total increase in minutes spent on digital media since 2013 and now account for just over 54 percent of digital media usage. As of December 2015, the report said consumers spent just over 13,125 hours consuming digital media on smartphones.

When smartphone usage is combined with time spent on tablets, the proportion of time spent consuming digital media on mobile devices rises to 65 percent. That figure is up 12 percentage points from 53 percent in 2013 and represents around 15,805 hours of digital content consumed on smartphones and tablets.

By contrast, the number of minutes spent consuming digital media on desktop devices has actually dropped by one percent since 2013. Further, as mobile’s proportional share of time spent has increased since 2013, desktop’s has decreased, dipping 12 percentage points from 47 percent in 2013 to just 35 percent in 2015. Desktop now accounts for only around 8,336 hours of digital media consumption.

Perhaps predictably, millennials (ages 18-34) are the age group with the highest mobile usage, with a near-universal 97 percent reporting they use a mobile platform to consume digital content. Interestingly, a full fifth of millennials said they are mobile-only consumers who don’t use a desktop device at all. The percentage of millennials who said they only consume digital media on a desktop device was a meager three percent.

Nearly a fifth of time spent on digital media is devoted to social networking, with the vast majority (61 percent) of that consumption occurring on a smartphone app.

As time spent on mobile devices has increased, so have the screen sizes. Since September 2014, devices with a 4.5-inch screen or larger have seen the greatest increase in adoption, while ownership figures for tablets and smartphone with screens smaller than 4.5 inches have plateaued and decreased, respectively.