New search suggests Apple's App Store is populated by apps that get next to no downloads (Zombies)

Figures seen by the BBC from tracking service Adeven indicate over two-thirds of apps in the store are barely ever installed by consumers. However Apple has said that 90% of all apps in the marketplace - which is marking its five-year anniversary - are downloaded at least once a month. Apple boss Tim Cook said the store had "fundamentally changed the world". Speaking to app developers at the firm's recent developer's conference, the chief executive said: "Customers love the buying experience and they love your incredible apps. And they have now downloaded 50 billion apps. "That's a lot of zeros and a truly staggering number." But according to Adeven the size of the US firm's app store, which has about 900,000 products, has left many developers struggling to get noticed. "579,001 apps out of a total of 888,856 apps in our database are zombies," the analytics firm said. It defines zombies as apps which never appear in Apple's master-list of the most downloaded apps worldwide, a chart which runs to over 300,000 places. "We can't say exactly how many downloads they have - Apple doesn't reveal this - but it is very small." Adeven's research follows on from another survey conducted by Pew Research Center's Internet & American Life Project. It indicated that some 68% of smartphone owners used five or fewer apps on a weekly basis, with many of their other "impulse" buys losing their appeal almost instantly. App developer Malcolm Barclay told the BBC that the amount of "zombie" apps was not a surprise - but argued that there was "safety in numbers". "There's a lot of apps in the store that are not downloaded for good reason, they're awful. "It's about making yourself attractive. If you have an attractive application that does what it sets out to do, Apple will help it get noticed." Zombies aside, the launch of the App Store in 2008 is widely regarded as a game-changing moment for how we consume technology. It has inspired other companies to follow suit, with Google, Microsoft and Blackberry among those to have launched their own stores.Apple says it has paid out $10bn (£7bn) to app developers - three times more, it boasts, than all the other app stores combined. The "app economy", as it has become known, has also been responsible for disrupting the video games industry. Companies such as EA have shifted to offering downloads of many of their titles for free, and make money through in-app sales of power-ups and other add-ons. Those that do charge an upfront fee are still relatively cheap. In particular, the popularity of Rovio's Angry Birds - which has made millions through franchising and merchandise sales - has made some games publishers consider if the established model of charging £30 or more for console and PC titles could become a thing of the past. Even so, the development has not been without controversy. Apple, which takes a 30% cut of all sales through its online marketplace, was recently forced to offer refunds to parents who had found themselves facing unexpected bills as a result of in-app purchases by their children