Well look, another report by a company that has a vested interest in mobile security. With a company who makes money off the fear of malware, is it any surprise they found large numbers. This study seems to be fairly useless due to the biased view on the subject of the company performing it, if it was an independent body I would put more trust in it.
The areas with the largest number of reports don't have access or have limited access to paid apps, due to low income or no support for buying apps in the country, so they get them from other sources.
Basically this report is useless as it isn't done by an independent body and the likely source of these is probably from cracked / pirated apps. So no need to worry if you are sensible and use caution when installing apps that look suspicious, and use a trusted market ( Play store, Amazon etc.) to get your apps from.