Observed density distribution of the 24 μm sample in NUVrK diagram in four redshift bins, color coded (yellow-to-gray), in a logarithmic scale (step =0.15 dex) and normalized by the maximum density. For comparison we show as a solid red line the 50% contour density for the K-selected star-forming population (K ≤ 23,5). We overplot tracks for BC03 models with different e-folding times (τ = 0.1 Gyr, red line; 1 Gyr, purple; 3 Gyr, orange; 5 Gyr, green; 30 Gyr, blue). Symbols mark the model ages at t = 0.1, 0.5, 1, 3, 5 Gyr (filled squares) and t = 6.5, 9.0, 12 Gyr (open squares). For the model with τ = 5 Gyr (thick green lines), we also show the impact of subsolar metallicity (Z = 0.2 Z⊙: thin line) and dust attenuation (SMC-like extinction law: long dashed line and Calzetti et al. 2000 law: short dashed line) assuming a reddening excess E(B − V) = 0.4. The thick black line in the top-left of each panel delineates the region of quiescent galaxies.