In the background we show the distribution of the lifetime of the ionized regions before their first major merger as a function of the appearance time of the regions. The color code is in arbitrary units with blue values indicating a faint probability, while the red tones denote a high probability. The white curve represents the evolution of the mean value of the whole distribution, the shaded area stands for the 3σ uncertainty on this value. The dotted white line represents the best fit of the mean value according to the fitting formula described in Appendix A. Red, green, and yellow curves represent the same evolution for three classes of inner halo mass according to Table 2 (in solar masses for H200/S200 red: 10⁹ − 10¹⁰, green: 10¹⁰−10¹¹, yellow: >10¹¹, and for H50/S50 red: 10⁸ −10⁹, green: 10⁹−10¹⁰, yellow: >10¹⁰.