Smartphone apps account for half of all time consumers spend online, according to the “The 2016 U.S. Mobile App Report” released this week by web and mobile measurement firm comScore Inc. In fact, three out of every four minutes of digital time is on mobile devices, the report finds.

The report is based on June 2016 data from comScore’s 3,200 clients that subscribe to its digital behavior measurement products and an August survey of 1,049 adults who own smartphones. In the study, mobile devices refer to smartphones and tablets.

While time spent in smartphone apps accounts for the majority of consumers’ time, retail apps are a fraction of this time at 4% of mobile app time. Social networks, music and gaming apps are the most dominant reasons for the time spent in apps. However, among all hours that consumers spend online with retailers, 54% of them was through an app vs. on the web, comScore finds.

Eight of the top nine most-used apps in the U.S., measured by unique visitors in June 2016, are owned by Facebook Inc. or Google Inc., the report finds. The most frequently used apps, in order, are: Facebook, Facebook Messenger, YouTube, Google Maps, Google Search, Google Play, Gmail, Pandora Radio and Instagram.

The 10th most popular app is that of online retailing giant Amazon.com Inc., No. 1 in the Internet Retailer 2016 Top 500 Guide, with 67.5 million monthly unique visitors, a 55% year-over-year increase, comScore says. Three other retailing apps made the top 25 most-used app list:  Groupon Inc. at No. 22  with 30.2 million unique monthly visitors, a 40% year-over-year increase; Wal-Mart Stores Inc. at No. 23 with 27.8 million visitors, a 26% year-over-year increase; and eBay Inc. at No. 24 with 27.6 million visitors, a 10% year-over-year increase.

Whether a consumer uses an app could depend on where it lives on the device. Fully 70% of smartphone owners report that the mobile app they use most is located on their phone’s home screen. In fact 75% of consumers say they have purposely moved apps to the home screen and the top reason for doing so, say 59% of those making that move, was because of how often they use the app. Facebook’s app, for example, is the top-used app with 149.6 million unique monthly visitors. Among them, 46% of smartphone users have placed the app on their home screen, and it is one of the five most-used apps for 86% of smartphone users, comScore says. The average consumer spends 13 hours a month in the Facebook app, according to the report.

The report finds that many retailers send consumers smartphone alerts, known as push notifications, to remind consumers about their app. However, smartphone alert fatigue is growing, comScore reports  in its August survey, as consumers are less likely to agree to receive push notifications from an app this year compared to last year. Among consumers who have received a request for a push notification, 13% say they never agree to an app’s request for smartphone alerts, and 25% say they rarely do, compared with 9% who said never and 22% who said rarely in the year-ago period. What’s more, consumers are not downloading many new apps. According to the survey, 49% of consumers downloaded no apps for the three months ended June 30. Among the remaining 51%,  13% downloaded one app, 11% two apps, 8% three apps, 6% four apps, 7% 5-7 apps and 6% eight or more apps.

The report also finds:

• Of the total time spent online in June 2016, 58% was through a mobile app, 33% is on a desktop device and 8% is on a smartphone or tablet.. (These numbers don’t add up to 100% because of rounding.)
• Time spent in mobile apps grew 11% year over year, while time spent on desktop units decreased 11%. Time spent on mobile web sites increased 5%.
• Across every age group, time spent in tablet apps has decreased year over year. The largest drop, at 35%, was in the 35-44 age group, where the average person’s time spent on tablet apps fell to 17.3 hours a month from 26.6 hours a year ago.