Fraction of thin-disc stars, f_thin(=1 − f_thick), in the edge-on projection (with the bar placed along the x-axis) compared to the total (thin+thick) disc, at the end of the simulation run (t = 9 Gyr) for all thin+thick disc models with varying f_thick values. Left panels show the distribution for the rthickS models, whereas middle panels and right panels show the distribution for the rthickE and rthickG models, respectively. The values of (f_thick) vary from 0.1 to 0.9 (top to bottom), as indicated in the left-most panel of each row. For each model, the fraction of thin-disc stars decreases with height from the mid-plane (z = 0). In addition, the appearance of the b/p structure changes from more X-shaped to more boxy-shaped as the thick-disc mass fraction steadily increases.