While almost 4 in 5 of the Chinese population are lactose intolerant, nearly 100% of Danes can drink milk without any “undesirable effects”. It’s worth bearing in mind that, generally, Northern Europe gets by fairly well: 70 to 90% of adults in these regions are able to digest milk. It is notable that the further south one goes, the more widespread lactose intolerance is: 50 to 75% of the populations around the Mediterranean and up to 80% of sub-Saharan Africa.
As for Asia, it holds the record for lactose intolerance at 90% or more in some parts of the Far East where adults cannot drink milk without suffering serious digestive problems.
A very short and informative report can be found on Arte which explains these “digestive” differences in our organisms across the ages.