In reality, this region has always been the most sparsely inhabited area in the horn..
i.e. Majeerteenia (#Puntland) made ~ 4.8% of the total population of Somalia (pre union). Remember this %.
This is equivalent to 4.8% of the total population (rings a bell? Hint: see 1931 above).
Otherwise the population of the #Puntland (Majeerteenia) would fall to the usual figure of ~5%.
No other explanation of consistent historic low figures in 1931, 1963 and 1975 suddenly changing post civil war.