Yes most measurements are BMI and it works for most of the population. But you used the same BMI to show that 200m+ were healthy. When using BMI for individuals there is more of a risk than for large populations.A lot of the stats are based purely off BMI which doesn't account for muscle.
That puts many elite athletes and generally muscular folks as obese when they may in fact have a very low body fat %
Like I've said many times before - stats are really useful, until you question the source. And then they're not.
Stats are really useful when you question the source and they are used correctly.