Temporal evolution of the growth/decay rate of the bar strength (dS​_bar/dt), for the thin-, thick-, and total (thin+thick) disc components for all models with varying f_thick values. Left panels: evolution for the rthickS models, and the middle and right panels: evolution for the rthickE and rthickG models, respectively. The f_thick values are indicated in the left-most panel of each row. Top middle row: growth/decay rate of the bar strength for the thin-disc-only model (f_thick = 0).