Google can find what is more or less in demand by the general mass of people.
What a lot of people are looking for by entering search queries.
Simultaneously with browsing, a certain part of people specifically publishes some information, promotes its search, so that it is easier to find it.
And also, along with all this, there is a lot of data in the form of files, web pages, applications that simply exist, but no one is selling them. Or, conversely, hides their existence.
Google can only find what is open to its bots.
As for percentages, they will never be accurate or approximate, that's why the Darknet will be.
It is unlikely that there will be a Darknet more than a regular network.
This thesis is formulated as follows: "Google considers the nth percent of text information on the Internet to be of high quality." So the wording "may find" is generally irrelevant.
And yes, you can explicitly ask Google not to index the site or part of the site.
About the "percentage of hidden information" in the question is written outright nonsense. Most non-indexed sites are just a repository of non-original information. Or meaningless information. Or information that is logically worthless, i.e. generated by bots.
Sheer nonsense, invented on the imageboard. In DeepWeb you will find a maximum of trading platforms where you can buy drugs, weapons, order murder. There is nothing else there. You simply cannot find some information, because you do not have access to it, due to the fact that this information is protected. You can find everything on the Internet: from state secrets to intimate photos of your girlfriend. It's just that most people don't know how to search for it correctly or simply don't have access to it.
Lol, no. The Deep web hosts at most several thousand sites with similar content. Mostly trading platforms. And yes, I ask you not to confuse the Dark net and the Deep web, as they are different concepts
Yes and no. In fact, despite the fact that the darknet does exist, you are inappropriately confusing the "real" darknet, such as onion sites and the i2p network, and its contents, with a part of the Internet that is invisible to google. Yes, there really is a part of the web that is invisible to google, but, basically, this is some completely uninteresting technical and service information, sometimes all sorts of "non-web", some "shining" outside snmp, and so on, or temporary data ... Google does not collect such "not interesting" (to him and to the mass user) information, and, perhaps, its volume is quite significant. But mostly, this is true "information garbage".