Energy evolution of the primary fractions (top panels) and evolution of differential fluxes of individual primary species as functions of energy (middle panels) and rigidity (bottom panels) using QGSJET II-04 + ΔX_max (left panels) and SIBYLL 2.3d + ΔX_max (right panels). The primary fractions were obtained by fitting the Auger X_max distributions (A. Aab et al. 2014a), while the total differential flux of cosmic rays was taken from A. Aab et al. (2020b). The two types of parameterized energy evolution of the primary fractions, see Section 3, are represented using dashed and solid lines in the panels.