We don't get much sun. As such, I have been supplementing with 10,000/day for the past 8 months. I just got my results back as 87ng/mL, which I believe is 217nmol, so slightly high perhaps, but within the target range.
And if there were any VitaminD to synthesize, my fair skin which burns in 10 mins in summer would do it.
I recommend supplementing on the high side and then testing. Incidentally, my initial Vitamins test was around 13 or 31nmol, so I've come a long way. I wish I'd done a large one-off dose, but didn't know and started with 5000/day.
Interestingly enough, my lab company lists the normal range as 30-100 (73 - 244), so things are moving.