Distribution of integrated SFE ϵ_int as a function of the total baryon surface density Σ_tot. Top panels: Distribution of all cloud samples with SF. Bottom panel: Results for the clouds formed more than 100 M_⊙ in newly formed stars. The data points are color-coded by the normalized density in log-space estimated by a Gaussian kernel. The green curves show the median values, and the shaded regions indicate the 16–84 confidence levels. The dashed curves denote Equation (5) with the best-fitting parameters from Li et al. (2019) for f_boost = 1, 3, and 10. Although the scatter of the simulated results is large, the median curve roughly follows the theoretical curve with f_boost = 3. The 16–84 confidence level lies between the f_boost = 1 and 10 curves at all the stages.