Age distribution of stars in BW using the formula of Martig et al. (2016). Only sources with 4000 < T_eff < 5000 K, 1.8 < log  g< 3.3, [M/H] > −0.8, −0.25 < [C/M] < 0.15, −0.1 < [N/M] < 0.45, −0.1 < [(C + N)/M] < 0.15, and −0.6 < [C/N] < 0.2 were taken into account. From a bootstrap analysis on generalized histograms (kernel 1.5 Gyr), mean trends (solid and dashed grey lines), and error bands to the ± 2σ level (shaded coloured areas) are derived for metal-rich and metal-poor stars (cut at [Fe/H] = −0.1 dex) as percentiles of the 600 bootstrap resamplings.