Apps are largely driving digital media consumption on mobile devices, but it’s becoming more difficult for programmers and other media companies to entice consumers to give new ones a spin.

That’s a key takeaway from a new study from comScore, which found signs that the industry has reached a “peak app” phase as consumer interest in new apps starts to wane.

Per the company’s 2017 U.S. Mobile App Report, app users across all age segments access 20 or fewer apps each month.

Despite concentrated usage, apps are clearly the main driver for digital consumption on mobile devices.

In a look across the top 500 mobile apps and the top 500 mobile web properties, comScore found that the average user spent 16 times as much digital media time with top apps than with top mobile websites, though the mobile web still tends to capture bigger audiences.

Digital media usage time on mobile devices is led by smartphone apps (50%), then desktop apps (34%), tablet apps and smartphone web access (7% each), and web access via tablets (2%).

Smartphone apps are more concentrated among younger viewers, as two-thirds of viewers age 18-24 spent their digital media time on smartphone apps, versus a 50% average among all age groups.

A big challenge for media companies is getting consumers to try their apps, comScore found, as the majority of smartphone users don’t download any new apps in a given month, and the average user downloads just two. The most common app discovery channel remains app-store searches (20%), compared to word of mouth (15%) and advertising and marketing (10%).

Consumers age 18-34 are also more willing to pay for apps, as one out of five downloaded an average of one paid app per month, and nearly half made five or more in-app purchases on an annual basis. The study also found that Facebook, Google and their associated properties own the top six (and eight of the top 10) most-used apps. By time spent, the top category is entertainment and communications (20%), followed by music (18%) and multimedia (10%)

In what could lead to a whole new definition for the term “sexting,” mobile users are expected to drive future viewership of adult content, according to U.K.-based research firm Juniper Research.

According to its recent report – Digital Adult Content: Market Trends, Forecasts & Revenue Opportunities 2015-2020 – Juniper estimates that more than 136 billion adult videos will be watched globally in 2015. That number will grow to 193 billion by 2020, Juniper said, fueled by smartphone users. According to Juniper, each smartphone user of adult content is expected to watch 348 adult videos this year.

The U.S. will see the greatest growth – video views are predicted to grow by nearly 55% in the United States by 2020 – while Western Europe will see a modest increase. In developing regions, the increasing availability of 4G and WiFi as well as smartphone and tablet ownership is expected to drive adult video streaming uptake.

While Juniper said that revenue growth will be steady over the next five years, specific pockets such as videochat and web cam offerings are expected to outpace the overall sector, mainly because they are purchased on a subscription basis rather than a pay-per view basis.

As in the past, the proliferation of free content could hamper growth.