When it comes to apps, it seems people are as adventurous as 80-year old grandmas. 

There are billions of apps out there (1.2 billion in the App Store and 1.3 billion in the Play Store), however, users have mostly shunned new apps and have stuck with ones they've already downloaded. 

According to data from research firm ComScore, 65.5 percent of American smartphone users neglected to download a single app in a typical month. In its latest mobile app report, the company said that most of the remaining users that committed to a download only took in one or two apps. Only a small fraction of smartphone owners in the United States downloaded more than four apps per month. 

The figure is surprising considering the rest of the report's contents. According to ComScore, mobile usage in the country increased by 52 percent since last year. American smartphone users also exhibited a high level of dependency on apps. The report said that 57 percent of smartphone owners used apps for every day of the month. For tablet users, the figure was at 26 percent. In its report, the research firm also said that for every eight minutes of media consumption on mobile devices, seven minutes went through apps. 

"While the meteoric growth of apps transpired quickly, this shouldn't come as too much of a surprise... After all, apps are the fuel that is driving mobile's growth and where most of the devices' utility comes from," the report read. 

One explanation for people's reluctance to download new apps may be that most are already satisfied with the ones they have. The top 25 ranking for the most popular apps across all operating systems show a preference for established apps. Not surprisingly, the most popular app among American users was Facebook. The app for the social network attracted about 115.4 million unique visitors last June. Youtube, on the other hand, had 83.4 million users. Other apps in the top 25 ranking include Google Play, Pandora, Yahoo and Instagram.

Another explanation may be the difficulty of finding new apps. With billions available on competing app stores, new players are being overshadowed by brands that people already know.  This brings up one of the biggest criticisms of App Store. Apple has received criticism for the discovery features in its marketplace, which mostly depend on popularity charts.