In the 1980s, their average incomes grew at 2.4 per cent per year. No less than fifteen of them had income growth of at least 0.8 per cent a year. Only two saw incomes decline. There are some direct links. With faster population growth, there is a higher ratio of workers to non-workers.
Workers have less surplus to set by, so savings rates are lower.
World Bank data from 76 developing countries show that the 38 with fastest population growth during the 1980s had average savings ratios of only 12 per cent of Gross Domestic Product in 1989. In the 38 with the slowest population growth the savings ratio averaged 18.5 per cent. Another factor is that, where population growth is rapid, a lot of investment has to go into keeping up the level of capital for each worker, rather towards improving it. But there are other factors which are probably more decisive, especially education, nutrition and health levels and more women working outside the home. All these lead to slower population growth and to faster economic growth.