Upper panel: linewidths with errors from three different samples, with probability distributions obtained by adaptive kernel density estimate (Silverman 1986): black symbols and line are from this work, orange symbols and dashed-dotted line are the J_up ≥ 2 CO linewidth distribution in unlensed SMGs (Bo13) and the green symbols and dashed line represent the linewidth from the J_up ≤ 2 CO lines of the lensed SPT sources (Aravena et al. 2016b). Our lensed sources with μ> 5 are indicated with open circles while the other sources are shown in filled circles. We note that although there is no lensing model for G12v2.43 and NAv1.144, it is suggested that their μ are likely to be ~10 (see Sect. 4.2 and Fig. 6). Thus, they are also marked with open circles. Lower panel: cumulative distribution of ⟨ ΔV_CO ⟩ for the three samples with the same colour code.