with the exception of south africa all of the briics countries experienced large increases in material extraction when average income rose indicating that material extraction rises rapidly at relatively low levels of income when average income grows this is likely attributable to the high rates of population growth typical of lower income countries and to the strong connection between the size of the population and the use of materials especially those required to fulfil basic needs but there appears to be two distinct trends for oecd countries with average incomes exceeding usd