Japan is the top country by median age of the total population in the world. As of 2015, the median age of Japan's population was 46.35 years. The top 5 countries also include Italy, Germany, Portugal, and Bulgaria. The median age of the population in Japan increased from 28.78 years in 1970 to 46.35 years in 2015 growing at an average annual rate of 5.45 %.
The median age of the population is an age that divides the population in two parts of equal size, that is, there are as many persons with ages above the median as there are with ages below the median. It is expressed as years.