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.
By 1890 the proportion of the population under age 15 had fallen to 35.5 percent, in large part because of the declining birthrate. Only 3.9 percent of the population was over age 65. The median age of the population that is, the age at which half the people are older and half are younger had risen to 22.By 2001, the proportion of the population under age 15 had fallen to 21.1 percent, while 12.6 percent of the population was over age 65.nly 3.9 percent of the population was over age 65. The median age of the population that is, the age at which half the people are older and half are younger had risen to 22.