Horrible things like this have happened throughout history but, as other posters have mentioned, increased media tools and increased awareness, have enabled these types of offence to be more reported. I do think, however, that these types of crime are increasing as time goes on. The recognised effect on some victims of sexual abuse is that they go on to be abusers themselves, thus one victim, later in life, may create twenty victims. Out of those victims, some will create more victims, and so on.
Added to this is the availability of sexual-related images, topics, advertising etc to younger people. None of this excuses what this vile youth did, but I fear that increases of this type of crime are inevitable.