Apple's App Store is continuing its massive growth, with app intelligence company Sensor Tower predicting that the number of apps it hosts will more than double over the next four years and reach 5 million apps by 2020.

Such prediction means that the App Store will be 73 percent larger by the end of 2020 compared with the size that Sensor Tower is expecting by the end of this year.

The report by Sensor Tower is based on the analysis of historical data and trends beginning with the launch of the App Store in 2008 until today, utilizing the company's own App Intelligence platform. The company came up with figures representing the worldwide active apps on the App Store at the end of each year as opposed to the number of apps released or expected to be released in the corresponding years.

At the end of the 2008, the App Store only hosted 5,000 apps. By the end of 2015, the number has ballooned to 1.75 million apps, and currently, there are just over 2 million apps on the App Store.

Sensor Tower expects the App Store to host 2.93 million apps by the end of this year, with an expected 2.13 million apps to be added from the end of 2016 until the end of 2020, increasing the figure to 5.06 million apps.

Further analyzing the apps being added to the App Store every month, Sensor Tower found that of the 48,231 new apps that were launched in May, games made up 43 percent with almost 21,000 new apps for that month. The rest of the top five categories were education, entertainment, business and lifestyle, but even combined, the apps released in May under these four categories did not reach half the number of games released that month.

With the growing App Store, the challenge for both developers and Apple is to make sure that users are able to discover the apps that they are looking for. Apple has started addressing the issue with a For You tab, which will be added to the App Store and will recommend apps to users based on what they have previously purchased and downloaded. 

However, Sensor Tower believes that more significant upgrades are needed to the curation, navigation and overall presentation of Apple's App Store in order to provide a stable foundation for an ecosystem that will double in size in just four years.

Apple was recently involved in a controversy over the App Store, as the music streaming app Spotify accused the company of denying approval to updates on the App Store in order to eliminate competition with Apple Music.