Observed abundance ratios between seven pairs of O-COMs. Data points in blue and red correspond to the five low-mass sources from the literature and the 14 high-mass sources from the CoCCoA survey presented in this work, respectively (the same as Fig. 4). If the column densities of one species in the pair are upper limits, the ratios would be upper (lower) limits, and the data points are then shown as downward (upward) triangles instead of circles. Square data points without error bars indicate that the column densities of both species in the pair are upper limits. Dashed lines in panels a-d indicate a ratio of one. In panels e-g, the gray shaded areas with slashes or crosses indicate the ranges of the experimental results in Chuang et al. (2017), and the green shaded areas indicate the simulation predictions by Simons et al. (2020).