I have no idea where they're getting that number from. The relevant search terms is "Deep Web" (not to be confused with the Dark Web). https://www.sciencedire

I have no idea where they're getting that number from. The relevant search terms is "Deep Web" (not to be confused with the Dark Web). https://www.sciencedirect.com/science/article/abs/pii/S0306437913000288 https://www.sciencedirect.com/science/article/abs/pii/S03064... The abstract from that article has a good introductory summary.