Basically, they seem to have 42% of websites with ads. The target audience of this article is advertisers and Google's own brand is based in part on their abili

Basically, they seem to have 42% of websites with ads. The target audience of this article is advertisers and Google's own brand is based in part on their ability to enforce a lot of standards that brands like, so brands expect them to have little presence on porn sites, hate sites, sites with malicious content, etc.