Initial eccentricities of test particles captured by the leading island (red) and trailing island (blue) at different migration rates of Neptune. The box plots indicate the minimum, maximum, median, and upper and lower quartiles as usual. The solid diamonds are the mean value of eccentricities. The L/T ratios are plotted as solid circles and are connected by a dotted line (right ordinate). The total capture efficiencies (in percent) are labelled at the top of the panels. The upper and lower panels correspond to fast and slow migration rate ranges, respectively.