Average population diagrams of ¹²CO corrected for optical depth. The measured average, first quartile, third quartile, fifth percentile, and 95th percentile associated with our sample of level populations corresponding to J_up = 1, J_up = 2, and J_up = 3 are indicated for two adopted values of the ¹²CO/¹³CO isotopic ratio (¹²CO/¹³CO = 60 in black, ¹²CO/¹³CO = 100 in red). The black solid line represents the linear fit of the black data points. The boundaries of the filled areas are defined by the linear fits corresponding to the first and third quartiles for each value of the isotopic ratio adopted. The 5th percentile and 95th percentile are indicated by the caps, the first quartile and third quartile are indicated by the ends of the box, and the average is indicated by the cap inside of the box. Each diagram accounts for a sample of measurements performed in one of the spatial boxes defined in Fig. 6 and integration ranges defined in Table 6: (a) the shocked clump, (b) the cloudlet, (c) the ring, (d) the ambient cloud, and (e) the shocked knot.