Fig. 5: RI-D’s temporal changes.

a Regions with Minimal Decline (2021’s D–2009’s D 0.1); b Regions Fluctuating within the Same Grades (Comparing 2021’s D with 2009’s D); c Regions with Minimal Increase from “Close to Acceptable” to “Acceptable” (2021’s D–2009’s D 0.1); d Regions with Notable Increase from “Close to Acceptable” to “Acceptable” (2021’s D–2009’s D 0.1); e Regions with Increase from “Acceptable” to “Close to Average”.