Most processed food uses uniodized salt iirc, which is actually becoming a problem in parts of the USA where populations eat nothing but processed food.
So if Switzerland imports a lot of those, raw, or in prepared/processed food, or even the animal feed for its hens and cows the Swiss today probably already get much more iodine in their diet than 100 years ago.
0. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
But the point is that Switzerland's environment is especially poor in iodine hence the specific health problems it used to have, and which were much less serious in neighbouring countries.
Link to an academic article discussing how the USA is now in the dangerzone of iodine deficiency.
https://link.springer.com/article/10.1007/s12011-018-1606-5#....