Number of objects versus rotational rate in cycles/day: two different samples are plotted: the sample without the centaur population (number of objects (N) = 92, black bars), and the sample without the centaur and binary populations (N = 64, gray bars). A Maxwellian fit to the first sample gives a mean rotational period of 8.86 h (σ = 1.697 ± 0.177, continuous black line). The second Maxwellian fit of the sample without binaries nor centaurs gives a mean rotational period of 8.64 h (σ = 1.741 ± 0.217, continuous gray line).