[C/O] ratios as a function of [O/H] using the oxygen line at 6158 Å for the thin-disk, thick-disk. and hαmr stars. The running means were calculated using windows of 30, 15, and 10 for thin-disk (yellow line), thick-disk (blue line) and the hαmr (red line) stars, respectively. These numbers reflect the sizes of each sample. For these populations, the 1σ uncertainty in the moving mean is also shown as a shaded region of the corresponding colour.