Evolution of half-mass Roche-volume filling factor λ as a function of the bound mass M/M_⊙ for SFE = 0.15, 0.17, 0.20, 0.25,0.30, and 0.35 with λ₀ = 0.09. The blue coloured palette curves represent r_apo = 10 kpc with e = 0, 0.5, and 0.33; while the red coloured palette curves represent the same, but for r_apo = 3 kpc. Solid curves represent the data for Z = 0, and dashed curves represent Z = 0.2 kpc for r_apo = 10 kpc and Z = 0.06 kpc for r_apo = 3 kpc. The cyan curves represent data for λ₀ = 0.045 for r_apo = 10 and e = 0. The distribution of the observational OC data from Gaia DR3 is shown in light red, and that from MWSC is shown in light blue.