I'd wager it's the same in all the Nordic countries, at least it's the same here in Sweden.
A couple a months ago when I spoke to my dad, he told me he had a checkup because he had been unusually tired, turned out that the only thing the testing showed was that he had d-vitamin deficiency.
What surprised me is that he was given prescription d-vitamins, since you can buy them anywhere without prescription.
Also there is vitamin D2 and D3. The normal stuff you take is called D2. The D3 is made by the kidneys from converting D2. But those with certain diseases, the kidneys don't do the conversion so they provide vitamin D3 in the form called calcitriol. Its something I need to take due to my kidney failure.
Calcitriol is actually the most confusing of my medications to manage since the dosage needs to be adjusted based on monthly blood tests. Things like amount of sun exposure can swing my numbers around. And it interacts with so many blood test numbers like PTH, phosphorus and calcium levels.
The dosage did work out to be 50x what was in the standard products though.