Panel a) specific star formation rate as a function of stellar mass in bins of redshift. For all redshift bins the data are fitted with a broken power law with slope a_low, holding below a critical mass (M_knee), and a_high holding above M_knee (see Table 2). The blue line connects the loci of M_knee for the various redshifts. Panel b) position of the M_knee as a function of log (1 + z). Panel c) specific star formation at M_knee. Panel d) slope below and above M_knee (a_low and a_high). The position of M_knee and the specific SFR at M_knee increase approximately as (1 + z)², while the mass quenching (given by a_high) becomes less efficient with increasing redshift.