I wonder if in the west it's partly due to the oldies dying off. We can only have our lives extended so far by modern medicine and good living conditions and the vulnerable housewives and the stalwart husbands who came in during the 1950's and 1960's as young (under 40) adults are hitting their 80's and 90's now.
I know that in the three halls sharing in my neck of the woods that about nine oldies have died from last memorial to this one.
And I reckon there are at least another 50 or so in their mid-late 70's upwards in the three congos. No one coming in either - birth rate virtually non existent!