The good thing about Bootstrap is that it is stamped on pretty much every page of a site. Our sample index was mainly front pages so it was easy to spot. Total size of the web is a very hard number to pin down. Verisign quote 252 million base domains worldwide across all TLD but we have some base domains in our index with over 1m sub domains.

Are there many sites not indexed by google a person would care about?

I think no one would miss a thing if we dropped all pages past 5 from the index :P