Population Density

There is a bug in population data. The population density becomes lower, if the resolution of a data set is increased. Reason: The values are measured per grid cell. Therefore, a finer resolution lowers the absolute value measured per grid cell. Therefore, the size of a grid cell needs to be considered for the return statements, so that the coarser and finder population density data can be compared. Furhtermore, the return value shouldn't depend on the grid cell anyway.

changed milestone to %New Datasets

added bug label

Comment: The mean calculation must regard the grid size and the number of grid cells!

Another comment: After all, is a max value comparable? Must it be divided by the grid cell size?