Left hand panel: incidence rates from the two legacy samples of strong Mg ii absorbers with points representing bin sizes with 6 and 20 absorbers in the XSGRB and XQ-100 samples, respectively. The grey line illustrates a sliding redshift binning of XSGRB absorbers and the shaded region presents the 68% confidence levels. The blue shaded region represents the 68% confidence intervals for a similar sliding redshift binning of the XQ-100 sample. Right hand panel: comoving line density. The dotted line represent strong Mg ii absorbers in quasar spectra (Mathes et al. 2017), and the grey stars mark a larger sample of quasar absorbers at high redshifts (Chen et al. 2016).