Nielsen’s 2013 Mobile Consumer Report details what users from various countries do with their smartphones.
Even with operating systems that offer consumers high-speed connections, built-in multimedia features and access to a multitude of apps, text messaging is still one of the most popular mobile activities among smartphone owners in all countries. South Korean smartphone owners are generally the most active when using their smartphone for multimedia or commerce activities such as web browsing and online banking, and Brazilians are the heaviest users of social media on their smartphones.
Only if you assume people are only allowed to do ONE thing on their devices. Personally, I don't know of ANYONE who uses their smartphones for only one thing. If they did, all it would do would be to work as a telephone.
This information is presented in the wrong way, making it hard to understand things at a first look.
It should be group by country, and the cake split by activity performed. Not the other way around.