I suppose this isn't including the tracking cookies and bowser fingerprinting bots that advertisers like to force on the users. If it did, that 5% would be 100%, since Google itself uses this practice.
Internet users: if you value your freedom, install tracking blockers, delete your cookies, don't be afraid to use anonomyzing services, (such as proxies, VPNs, or TOR), and avoid using services that intentionally track you. The latter point means not using Facebook and Google, while installing the fewest quantity of non-free programs possibly (0 is the ideal number). Also, broswer addons like NoScript and HTTPS Everywhere are also a good idea.