Distributions of the Si ii λ1526 equivalent width measured in ESDLAs (hashed black histogram) and in a sample representative of the overall population of DLAs (green Jorgenson et al. 2013). The vertical line corresponds to the equivalent width (the 1 σ error is represented by the grey area) measured in the stacked ESDLA spectrum. The inset shows the corresponding cumulative distributions (solid black: ESDLAs, dashed green: Jorgenson et al. 2013).