GLOBAL INVESTMENT IN ELECTRICITY INFRASTRUCTURE saturation effects in the OECD and catching up by the poorer developing countries. It also reflects changes in the structure of economic activities. Most of the economic growth that has occurred since the 1970s has come from services and light manufacturing industry, which generally require small amounts of electricity per unit of output. In contrast, heavy electricity-intensive industry has contributed more of the increase in GDP in non-OECD countries. The energy efficiency of electric equipment and appliances in those countries is also typically lower than in the OECD, boosting electricity intensity. Changes in the level and age composition of the population affect the level and composition of electricity demand, directly and through its impact on economic growth and development. A growing workforce will both boost the productive potential of the economy and lead to higher demand for electricity. The ageing of the population tends to increase the number of households and therefore per capita electricity consumption. Migratory movements in population also influence the need for new capacity and investment in production, transmission and local distribution. Migration to regions where capacity is already fully utilised will increase the overall need for investment, unless it relieves the need for new investment in those regions from which the population is migrating. The price of electricity, in absolute terms and relative to other forms of energy, also has a significant impact on demand and investment needs. The cost of supplying electricity is determined largely by the cost of building and operating power plants and transmission and distribution lines. Maintenance costs are low for most generating technologies and networks. The share of generation in the total cost of supply varies across countries, but is typically more than half. Fuel often accounts for a large part of the cost of generation, and therefore the final cost of electricity to end users. Depending on 