In Denmark anything less that 16.5% can be purchased by 16 year olds.

This is crazy. 16.5 is stronger than regular wine.

That's exactly the point. It's a middle ground ABV where there aren't a ton of products and below which are mostly fermented beverages and above which is distilled liquor.

I was talking about Germany.

In Switzerland, it is 16 for beer and wine, and 18 for spirits (or drinks that contain spirits, like "alcopops", even if they have a low ABV). I think Austria and Germany are the same.

Most US states, last I checked. Note: drinking age, not age to buy alcohol. Usually there's some rule about parental consent or only at home.

Belgium as well.