The first one is the Engels coefficient, which explains that the cost of daily necessities has dropped its percentage all through the past decade, in terms of family income, to about 37-some percent.
El primero es el coeficiente de Engels, que explica que el costo de las necesidades diarias ha disminuido su porcentaje a lo largo de la última década en materia de ingresos familiares, en cerca de un 37%.