Significant correlations after the addition of the Fe-K sub-sample. The S23 UFO sub-sample is shown in red dots, the T10 in blue diamonds, the C21 in black squares, and the Fe-K sub-sample in green diamonds. The best-fitting linear correlations, applied exclusively to statistically significant correlations, are presented by the solid black lines and the dark and light gray shadowed areas indicate the 68% and 90% confidence bands, respectively. In the legend, we report the best-fit coefficients, logNHP, and the intrinsic scatters for the correlations.