Earlier quoted context omitted.
How come that the disease wasn't widespread earlier?
In Slovakia, another landlocked country with lack of natural iodine from rainfall or diet, dementia became part of the culture. 30% (!!!) of population suffered from dementia. Iodizing salt raised IQ by 10 point every 10~ years but the damage is irreparable…
Oh, and here in Germany it's on place 6?! Wouldn't have guessed!