That explains why you were 10 times more likely to find something 15-20 years ago then you are today. They reduced the size by dropping a lot of sites and not

That explains why you were 10 times more likely to find something 15-20 years ago then you are today. They reduced the size by dropping a lot of sites and not crawling as much. We expect google to be at 100PB x 100 with the growth of users and content over that time period. Someone made the decision to prioritize a smaller size over a more complete index and some A/B test was run and turned out well.