Ohm. Because of that surface resistivity and the surface resistance are often mixed up. In order to differentiate between the two, surface resistiv-ity is often expressed also in Ohm/square (Î©/sq.) which is not a valid unit from the dimensional anal-ysis point of view. 2 Surface resistivity and surface resistance 2.1 Current density and surface cur-
The median age of the world's population was estimated to be 30.1 years in 2016, with the male median age estimated to be 29.4 years and female, 30.9 years.
Definitions. 1  Age distribution > Population aged 0-14: Percentage of total population aged 0-14. 2  Age structure > 0-14 years: The distribution of the population according to age. 3  Birth rate: The average annual number of births during a year per 1,000 persons in the population at midyear; also known as crude birth rate.