There are worse ways to spend an afternoon than perusing the Top Grossing charts of the big app stores, if you want to understand the dynamics of the apps market.

I wanted to crunch some data from the Google Play store for Android, to see what kind of apps are making the most money there, and particularly to look at what proportion of apps are paid versus free.

And? Here are the results of the analysis, based on the UK Google Play top grossing apps chart, as it stood in the afternoon of 20 April, with the data coming from the Google Play website.

The topline results: 75% of the 100 top grossing Android apps in the UK – on Google's store at least – are free to install, and make their money from in-app purchases. Note, all these figures are based on consumer spending, rather than advertising.

But what's even more clear is the dominance of one particular kind of free app within this, since 68 of the 100 apps are freemium games. In fact, 18 of the 20 top grossing Android apps in the UK were free games, led by Gameloft's Ice Age Village, Zynga's Zynga Poker and TinyCo's Tiny Village.

Meanwhile, of the 25 paid apps in the chart, 13 were games, meaning that games accounted for 81% of the 100 top grossing apps at the time my analysis was performed.

Getting back to the freemium games, you can see some names familiar from the iOS world, like Gameloft (four free-to-play games in the 100 top grossing chart), Glu Mobile (seven), Storm8 (five) and Teamlava (five), along with Zynga (three, or four if you count newly-acquired Draw Something, which still lists OMGPOP as its publisher). Others, like Game Insight and Droidhen, are more prominent on Android than iOS.

When you browse the Google Play store, each app is assigned into a bucket of "Installs" – a very rough guide to how many times it's been installed. The Installs figures are global rather than UK-specific, but they're still useful.

The sweet spot for freemium games on Android seems to be the 1m-5m installs zone, with 32 games from the chart falling into this bucket. Another 13 have notched up 5m-10m installs, and a select group of six are into 10m-50m territory (Ant Smasher, Drag Racing, Live Holdem Poker Pro, Tap Fish, Temple Run and Draw Something Free).

When you look at the paid games that have made it into the top 100, it's more usually 100k-500k installs for games like Cut the Rope: Experiments, Angry Birds Space Premium, Worms, Sonic CD and The Sims 3, although Where's My Water, the paid version of Draw Something and Minecraft have all made it to 500k-1m installs, and the original Cut the Rope is in the 1m-5m bucket.

The common theme there? All trusted brands, either from console/PC, or from sheer popularity on Android and iOS. Football seems to be doing well, too: both FIFA 12 and Football Manager Handheld 2012 are in the 10k-50k global installs bucket, but are still on the chart – the latter in 11th place with a £6.99 price.

Outside games, there are less obvious lessons. To get into the 100 top grossing chart, you can charge £20 or more if you have a certain kind of app, like navigation (CoPilot Live), sports (Golfshot: Golf GPS, F1 2012 Timing App) or medical (Anesthesia Central at a whopping £93.28, and 100-500 installs).

DocumentsToGo and Quickoffice Pro have been doing good business at just under £10 each too, with 500k-1m and 100k-500k installs respectively.

It's just a snapshot, and a snapshot of one country at that. But a useful one for gauging the evolving character of Google's store. It also shows why freemium games publishers are moving fastest from iOS-only to iOS+Android strategies.

What about Apple though? I fired up iTunes on my desktop and checked the iPhone Top Grossing chart in the UK, and found that 45 of the top 100 apps were freemium games, with another 22 being paid games - 67% overall.

Less than Google's store, then, but still a sign that a lot of the money being made from the world's two biggest app stores is coming from games, and free-to-play games in particular.

Here's the core data that I used for the analysis, if it's of use.