How should I interpret Figure 8? https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0281779.g008 https://journals.plos.org/plosone/articl

How should I interpret Figure 8? https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0281779.g008 https://journals.plos.org/plosone/article/figure?id=10.1371/... If the difference between the 2012 and 2020 cohorts is roughly the same as between the 2012 and 2002 cohorts, why should I suspect this isn't just a failure to pick comparable cohorts across the decades?