Number of objects classified by a certain number of visual inspectors in phase 1 (top panel: to select lenses and ring galaxies) and phase 2 (bottom panel: to select only the ring galaxies from phase 1). Objects selected by the seven visual inspectors represent a 100% in agreement among users, while the sum along the different bins give us the union, namely, the number of objects selected by at least one user. The exact number in each bin is shown at the top of each bar.