Host-galaxy neutral gas column density, N_ntr, against host-galaxy total gas column density, N_N,O, along the line-of-sight to a sample of 26 GRBs. For each GRB, N_ntr is derived from either the column density of Zn ii (red circles), S ii (orange squares), Si ii (green stars), or Fe ii (blue triangles), where a correction for dust depletion is applied to N_N,Si and N_N,Fe. Smaller data points correspond to those taken from low- or mid-resolution spectra, and larger data points are taken from high-resolution spectra (R > 10   000). The dashed line corresponds to where N_ntr is equal to N_N,O.