Distribution of the SDSS emission-line galaxies a) over redshift z; b) over extinction-corrected absolute- SDSS g-magnitude M_g; c) over total stellar mass M_∗; d) over mass M_y of the young stellar population; e) over the extinction coefficient C(Hβ); f) over the equivalent width EW(Hβ) of the Hβ emission line; g) over the extinction- and aperture-corrected Hβ luminosity L(Hβ) (lower axis) and the star-formation rate SFR (upper axis); and h) over the oxygen abundance 12 +log  O/H (h). Dotted vertical lines in all panels indicate mean values of the distributions.