The demographic trends in the GP aren't unique to America. They're more or less the rule in most developed countries, and I think it's safe to say most HN users probably come from developed countries.
Where I come from, it's pretty poor form to ask people to cite sources for obvious statements, without any other insight or commentary. After all, you're asking them to do work for you, but not taking basic steps to suggest you might appreciate their effort.
The preferred option is to do a little reading of your own beforehand, and to share whatever it is you know that makes you think the obvious answer might not be right.
