Scatter plot of the stellar sample on the [α/Fe]-[Fe/H] plane (similar to Fig. 1). Red circles represent thin-disk stars while blue circles represent thick-disk stars. Close-in small planet-host stars are marked by black dots. The division into four regions is based on cutting at [Fe/H] = −0.25 dex in addition to the division into thin and thick disks. For each region, we have marked the number and occurrence rates of detected close-in small planets as well as the detectability-weighted means of the stellar mass sample.