A country's color channel value is set to the fraction of the maximum world value of the corresponding property. This data can be divided by the areas of countries or by their population. You can use the logarithms of values and the resulting color intensities can be inverted.
Tooltips and ranking tables showing either the top ten or the last ten for each selected country property help to define and interpret these maps. If actual values for some of the 237 countries are not available, then the last ten can ignore them or not.