Cumulative distribution of systems in the simulation that have had their luminosity increased by at least some factor, given by the horizontal axis, in the past. The black solid line is the distribution of the sample presented in Sect. 3.1, while the red solid line is the distribution of the Jørgensen et al. (2015) observations shown in Fig. 5. The dotted line is for the same sample, but including binaries, while the dashed line include protostellar luminosities down to 0.05 L_⊙. The lookback time is 10 kyr.