Asymmetry ratio, at t = 5 Myr, for different migration rates of the giant planets, plus the in situ scenario. The yellow shaded region highlights the observed asymmetry ratio of 1.6 ± 0.1 found by Szabó et al. (2007) and the green shaded region represents the observed asymmetry ratio of 1.4 ± 0.2 found by Grav et al. (2011). The red line indicates the estimated asymmetry ratio of 1.85 ± 0.57 found by Nakamura & Yoshida (2008). In this latter case the shaded region has not been overplotted to keep the figure readable, but the uncertainty is indicated in the legend. Above each asymmetry ratio it is noted the corresponding migration Δa that Jupiter undergoes.