That is very misleading. Considering over 80% of mobile devices sold are Android devices, all things being equal you would expect 80% of the infections to be found on them.
A better presentation of the same report: Nokia Threat Intelligence Report: number of infected Android phones on the rise.
There is an app by the guardian project called checkey that checksums app.apk's pulls up the digital signature and other useful things. Its a good app.
