Has this always been going on? [Details in description]?

I have two children ages 13 and 16. I’ve noticed a lot of their peers are being raised by their grandparents… Has it always been this way or is this a new trend? I don’t recall many (if any) of my friends being raised by grandparents. It seems that 6 out of 10 (at least) of my childrens peers are being raised by their grandparents.