Column density values from the MADCUBA analysis of N₂D⁺ as a function of N₂H⁺ for all the positions analysed in this work, as well as literature values for LMSCs (Crapsi et al. 2005; Fontani et al. 2006; Friesen et al. 2013; Cheng et al. 2021), HMSCs (Fontani et al. 2011; Kong et al. 2016), HMPOs (Fontani et al. 2011), LMPOs (Emprechtinger et al. 2009; Friesen et al. 2013), and IRDCs (Miettinen et al. 2011; Gerner et al. 2015; Barnes et al. 2016). The average uncertainties associated to the data point from the literature are reported in the bottom right corner. Finally, dotted lines correspond to fixed values of D/H ratios.