Japan- One way is arithmetic density, or the number of people per unit of land. Japan's arithmetic density is 338 people per square kilometer.
Germany- The population density in Germany is 240 per Km2 (623 people per mi2). The median age in Germany is 45.7 years.
Argentina- Population density of Argentina increased from 8.6 people per sq. km in 1969 to 16.3 people per sq. km in 2018 growing at an average annual rate of 1.31%.