Probability distribution functions of proper motions for two circular regions centred at (ℓ, d_b) = (20°, 7.25 kpc) and (ℓ, d_b) = (−10°, 4.5 kpc), with a radius of 0.6 kpc and a galactic height |Z| < 1 kpc. The bin size is Δμ = 0.6 mas yr⁻¹ and the total area is normalised to unity. The first (second) column corresponds to the longitudinal (latitudinal) proper motion, while the first (second) values in the insets refer to the barred (axisymmetric) model. The position of the mean values and the ±1σ interval are denoted by triangles and error bars, respectively.