Google only owns and holds about 4 percent of the entire internet.
Google has in it's database and index about 6 to 7 million terabytes of data and the data added to it's database and index is always climbing everyday and every year as it indexes more and more content from websites online and from it's own websites such as Youtube etc.
Google doesn't own too much of the internet but it does own quite a bit of the internet.
Yahoo, Bing, Duckduckgo etc index a lot of content on the web too.