The top 10 is dominated by Facebook and Google, though Snapchat ranks for those under 35.

The popular narrative around the rise of the mobile web and smartphone apps has been one of increasing audience fragmentation. But the opposite may actually be happening — concentration and consolidation.

More digital media time is concentrated in smartphone apps than on the mobile web or PC. And most of that time is spent in a small number of apps, led by Facebook. Users are also downloading fewer new apps, so it’s getting harder to break through. Earlier today, comScore published its 2017 US Mobile App Report detailing these trends.

Digital media time spent with the desktop stands at 34 percent, with smartphone apps at 50 percent. Tablet and mobile web represent the remaining 16 percent. And though it sees dramatically lower engagement, the mobile web has roughly 2x the reach of mobile apps.

Above is the breakdown of digital time spent by age category. Those in the 18–24 age group spend the least time with the desktop, while those in the 65+ category spend the most. This data and other findings in the report contain clear audience targeting implications.

The report also presents the time spent by vertical with mobile apps. For example, 96 percent of time with maps happens in mobile apps. Less than half of retail engagement, however, comes via apps, while news saw the most growth in app time since last year.

Here’s the scary or helpful finding (depending on your perspective) in the data: The bulk of users’ mobile app time is concentrated in a small number of smartphone apps. Of the top 10 apps, Facebook owns three, and Google has five. By age category, however, the rankings are different. In particular, among 18–24-year-olds, YouTube was the top app, and Snapchat was number three. Google search is number six, while for those over 55, Google’s search app is second to Facebook.

Nearly 90 percent of users’ mobile app time is spent within a user’s top five apps. In the larger context of digital media time overall, that means just over 51 percent of all digital media time in the US is now being spent within users’ top five mobile apps. Comscore also points out that this concentration of mobile app time translates into a “significantly smaller long-tail than desktop and mobile web.”

Another trend that should potentially concern marketers is the flattening of app downloads. More than half the mobile audience downloads zero new apps per month. The other half is more active, but the numbers skew toward the lower end. Millennials buck that trend, with many saying they’re now downloading more apps than the did a year ago.

Mobile users under 35 also appear increasingly willing to make in-app purchases, with 70 percent making at least one in-app purchase in the past 12 months.

Another interesting finding is an apparent reversal of the anti-notifications trend. In the aggregate, people appear to be opting in to allow more notifications than a year ago, which comScore partly attributes to the current news climate.

Those under 35 years old are the most likely to agree to notifications. They’re also more likely than other age groups to be annoyed when they receive too many notifications.

There’s a great deal more in the full report, which can be dowloaded for free after registration.