Fig. 6: Land use efficiency of various urban scales at different ages (Unit: 100 million yuan/km2).

Polygons of different colors represent land use efficiency at various ages. The red polygon represents land use efficiency at age 0. A Urban land in 1995, B Urban land in 2000, C Urban land in 2005, D Urban land in 2010, E Urban land in 2015, and F Urban land in 2020.