MDFs of different orbital families of the MW bulge. The orbital families are classified according to the in-plane to vertical frequencies ratio: inner boxy orbits (f_z/f_x = 1.4–1.6), X-shaped orbits (f_z/f_x = 1.6–1.9), banana orbits (f_z/f_x = 1.9–2.2) and long bar orbits (f_z/f_x > 2.2) orbits. In each panel, the distributions are normalised to the maximum value. For reference, the vertical red dashed lines mark the locations of the peaks in the MDF based on the microlensed dwarf and subgiant stars in the MW bulge from Bensby et al. (2017). The same grey histogram in the background shows the MDF of the disc orbits with |f_z/f_r − 2| > 0.1.