Number of SNIa and SNII per century as a function of time for the boxy SFH shown in Fig. 2. As in Fig. 6, the orange lines are the results applying the IGIMF theory, while the blue lines apply the invariant canonical IMF. The thick lines below and the thin lines above are the rates for SNIa and SNII, respectively. The serrated shape is caused by the simplification that all the stars formed in a 10 Myr star formation epoch have an identical age.