5.5% of unique IPsmillions of usersaccessing Google sites that included some form of injected ads. Advertisers are generally only able to measure the final click that drives to their sites that drive traffic. Ad networks originate from ad networks that translate unwanted software installations into unwanted traffic via unwanted ad networks. Ad injectors source their ads from about 25 businesses that provide injection libraries. Superfish and Jollywallet are by far the most popular of these.”]
Source: https://security.googleblog.com/2015/05/new-research-ad-injection-economy.html