There are more than 7.4 billion people in the world. About 37,000 of them are in "uncontacted tribes" of which there are less than 200. Thus, all but 1 in 200,000 people on Earth have been contacted.
525 years ago, the population of the world was about 500 million, and the number of "uncontacted" people was on the order of 25 million or more. Thus, perhaps 1 in 20 people on Earth were "uncontacted." The proportion of the population that is uncontacted has fallen by a factor of 10,000 in the last 525 years (21 generations or less).