Age and gender weight by region. Population data is taken from Eurostat for all countries. Cross-tabulations from the population data were then collected and put together for each country and region and were compared with that of the cross-tabulations in the sample. The Iweights were calculated based on differences between the sample and population cells, such that demographic groups (older males for example) that were over (under) sampled relative to the population receive a lower (higher) weight.