Fractions of double-peaked LAEs plotted against the redshift. The unbiased sample has been divided into eight redshift bins with the same number of objects (25 or 26). The fraction of double-peaks has been derived in each bin. The results are positioned at the median redshift of each bin. The fractions of inclusive double-peaks are represented in black colour. The X_DP of restrictive objects are in orange. The horizontal black line at the top of the figure shows the size of each redshift bin. The black stars surrounded in red represent the mean Lyα luminosity of each bin.