(Top) Location in galactic coordinates of the sources in our sample. Obscured sources (F_9   μm/F_J > 100) are plotted with filled diamonds, whereas the open diamonds represent sources with lower obscuration (F_9   μm/F_J < 100). (Bottom) Galactic latitude distributions of obscured (left) and less obscured (right) sources in our sample. Exponential fits of these distributions, as described in the text, are shown by solid black lines. For comparison, similar fits (normalized to the first bin of the Galactic latitude distributions of obscured and unobscured sources) are shown for the samples of SOLE and DUPLEX sources of Siódmiak et al. (2008), for the samples of bipolar and elliptical PNe of Corradi & Schwarz (1995) and Stanghellini et al. (2002), and for the sample of optically bright post-AGB stars of Suárez et al. (2006).