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.
The rising life expectancy within the older population itself is increasing the number and proportion of people at very old ages. The âoldest oldâ (people aged 85 or older) constitute 8 percent of the worldâs 65-and-over population: 12 percent in more developed countries and 6 percent in less developed countries. In many countries, the oldest old are now the fastest growing part of the total population.