Distribution of the polarization properties for the stellar sample with a reliable parallax estimate. Distributions of the Stokes parameters (q’s and u’s) and of the logarithm of their uncertainties (log₁₀(σ_q) and log₁₀(σ_u)) are shown in the top and bottom panels, respectively. The horizontal and vertical dashed lines are used for visual reference. They indicate the q = 0 and u = 0 loci in the top panel and indicate the values of 0.1% and 1% in polarization uncertainties in the bottom panel.