Na i/Ca ii ratios as a function of log N_Na i. The red symbols show the DLA data (1.06 ≤ z ≤ 1.18) of Kondo et al. (2006, see their Fig. 5 for a detailed explanation of the different symbols). Black circles and crosses show the data for the Ca ii and Na i absorbers in Milky Way (Vallerga et al. 1993) and in the LMC (Vladilo et al. 1993), respectively. Purple symbols show higher-redshift absorption lines extracted from our sample (Richter et al. 2011). Filled circles show the ratios found in our MW halo sample, with deviation velocities colour-coded. The black solid line represents a power-law fit with slope β = 0.8 ± 0.1.