Also how come Yugoslavia 1 while Croatia is 2?
Well spotted. Probably Croatia was not meant to be there.
Since it is GDP above subsistence, this could be possible if Yugoslavia outside Croatia had a GDP under the subsistence figure, but almost surely this is either a math error for at least one of the two or a huge discrepancy from interpolating or extrapolating.
This is another interpolation anomaly as the first figures for Croatia alone come later than 1950. It is surprising how most of the world in 1940's was no more than twice the level of subsistence.
And it is reasonable to view natural resources as being more important for a war effort than their share of the GDP alone would indicate. An industrial economy can compensate for the lack of natural resources in many ways, these compensation techniques have costs of their own.
Romania is barely above subsistence.
I wonder if Maddison is consistently underestimating the per capital GDP's of European countries.