Fraction f(H₂) of hydrogen that is in molecular form in local gas/LVC, calculated from emission excess relative to the linear correlation (see text), versus the total column density estimated using the 857GHz dust emission transformed into gas column density using the emissivities ϵ_ν. Black points show the median value of f(H₂) in bins of N_H computed using all lines of sight in our sample. The error bars show the half-width at half maximum of the PDF computed in each N_H bin. Green symbols show the results obtained using UV absorption data from high-latitude surveys (Gillmon et al. 2006; Wakker 2006, squares) and toward O stars on lines of sight closer to the Galactic Plane (Rachford et al. 2002, 2009, triangles).