Ionised fraction of the IGM Q_H II with redshiftwhen f_esc is introduced as a parameter. Details on the origin of data points are given in the legend. ML models (continuous lines) are shown for various set of constraints: blue when all constraints are used, coral when Q_H II constraints are skipped, for which the 68% and 95% confidence intervals are drawn in salmon. These inferences are compared with a model forced to reproduce results from Robertson et al. (2015, R15, purple dotted line) and with the two evolutions used in Planck Collaboration Int. XLVII (2016, P16): redshift-symmetric as the dashed-dotted brown line and redshift-asymmetric in black.