It's every developer's dream: Win fame and fortune for creating a mobile app that sells like wildfire.

Unless you work for a huge established company, keep dreaming.

ComScore released a U.S. Mobile App Report this week and made some interesting discoveries. It found that nine of the top 10 most used apps were built by six huge tech companies: Facebook, Google, Apple, Yahoo, Amazon, and eBay.

If you cast a slightly wider net, the scene starts to look slightly better but still not great. Those same six brands account for 16 of the top 25, and 24 of the top 50 apps, ComScore found.

At the same time that those giants dominate the mobile app landscape, the majority of people don't even bother to try anything new. ComScore found that 65.5 percent of smartphone users download zero new apps each month. There's this small category of people -- 7 percent of smartphone users -- that downloads like crazy, accounting for half the monthly app downloads and skewing the average up.

It's not that people aren't using apps. ComScore found that seven of every eight minutes on mobile devices is spent in an app.

One possible explanation for why most people don't download new apps, including those from little-known startups, is that the app shopping experience is pretty poor. No one wants to scroll through lists of apps. App stores need a shake up and there's at least a hint that one might be coming, based on rumors from earlier this week that Verizon might be cobbling together a group of operators to build a new kind of Android app store.

There may also be an element of fatigue setting in with new apps. It would make sense if a novelty factor drove people to experiment with their first smartphone. Now that smartphones are more commonplace and people have been using them for years, maybe they aren't that interested in trying out new apps.

Also, it depends on how you define killer app. Games like Angry Birds break app download records  but you don't see it appearing in ComScore's list of apps that people spend the most time in. Depending on monetization strategy, that kind of popularity can still yield a big windfall, but typically only over the short term. 

Becoming a user's favorite app can really pay off. ComScore found that 42 percent of all app time spent on smartphones occurs on a user's single most used app. Nearly three out of every four minutes of app usage occurs on one of the individual's top four apps.

The challenge is figuring out how to get into that list of most used apps to rack up sustained profit.