Evolution of the galactocentric velocity (v) and the cylindrical components of the velocity vector (v_ϕ, v_R, and v_z). The figure shows normalised distributions, in 2D histograms with time bins of 10 Myr and velocity bins of 30 km s⁻¹, 20 km s⁻¹, and 10 km s⁻¹ for the solar neighbourhood, the thick disc, and the total population, respectively. For clarity, we set the maximum values of the distributions at 4 × 10⁻⁵ s km⁻¹ Myr⁻¹ ≈ 13 × 10⁻¹⁹ km⁻¹, even though the peaks in the last row exceed this maximum to a certain degree. The black lines show the mean velocities at each point in time.