You might already know, but anything/everything you do on Google, get's saved. They know every page of your website, who owns what website etc. More or less thanks to their analystics software, they know where your traffic is coming from, where it's going etc. I personally don't like this, what about YOU?
They know it as aggregated data. I'm not paranoid enough to think that they are interested enough in me personally, to have a Google staff member peeking into my stats on a regular basis And if they did all they find out is that I get 6000 visitors a month from the keyword 'chewing gum' - Whoop de doo. P.S. I don't really get traffic from the keyword 'chewing gum', paradoxically I'm happy for Google to know what my keywords are, not so keen on people reading this forum knowing.
Google probably knows everything else about me and so why not lol They have millions of visitors a day and so I dont think they will are interested in me.
Your bank usually knows everything about you - do you feel secure about this ? Rhetorical question. There's nothing you can do about it.
Google like to know lots about all websites on the internet in order to make their search results more relevant, and to see new trends in web development in order to see how our use of the internet is changing. They actually track all this data for themselves, rather than to invade our privacy.