* Actually, I think that the 99 % figure is fairly accurate.  A "native speaker" means someone who speaks Portuguese as first language. Well, Portuguese is NOT the first language of most Brazilian Indians who are, according to the latest Census, approximately 0.45 % of the population. Second, according to IBGE, something like 0.6 or 0.7 % of the population of Brazil is actually foreign-born (down from a historical peak of 5 % in the early 20th century and compared to a contemporary figure of 12 % or so for the U.S). Of course, that might look like a small number, but, still, excluding those born in Portugal, most of those foreign-born residents of Brazil do not speak Portuguese as their native language. Moreover, even among native-Born Brazilians, there are still a few homes where kids learn some other language (i.e. their "native language") before learning Portuguese. That is still the case for example in some German communities in the rural South. Overall, I would say that 1 % of non-native speakers of Portuguese is a reliable guess.