The Burgdöfer index is a graphical representation used in demography for the study of populations. This index compares the percentages of population in the population group between 5 and 14 years of age with those over 45 and under 64 years of age. When the first group is more numerous (percentage higher) the population is considered young; when both groups are approximately equal, we speak of a mature population and if the group of 5 to 14 is smaller, it is considered to be an aging population. The graphical representation is usually made by two rectangles proportional to both groups, similar to a population pyramid, but only with those two age brackets. This simplifies the study of large population databases. Bibliography
Sierra A, Doreste JL. Demography and public health. Static demography. In: Gil P. Preventive Medicine and Public Health. Barcelona: Masson-Salvat; 1991.
wiki