The size and growth of a country's population are both causes and effects of economic and social developments. The natural increase in population (births minus deaths) has slowed in all OECD countries, resulting in a rise in the average age of populations. In several countries, falling rates of natural increase have been partly offset by immigration from outside the OECD area.
The tables refer to the resident population. For countries such as France, the United Kingdom and the United States which have overseas colonies, protectorates or other territorial possessions, their populations are generally excluded. For full details, see Sources below.
Growth rates are the annual changes in the population and are the result of births, deaths and net migration during the year.
The total fertility rate is the total number of children that would be born to each woman if she were to live to the end of her child-bearing years and give birth to children in that period in agreement with the prevailing age-specific fertility rates.
For most OECD countries, population data are based on regular, ten-yearly censuses, with estimates for intercensal years being derived from administrative data such as population registers, notified births and deaths and migration records. In several European countries, population estimates are based entirely on administrative records. In general, the population data for OECD countries are reliable, although, for some countries, there are breaks in the series as indicated by vertical lines in the tables.
Note that for some countries the population figures shown here are not those used for calculating GDP and other economic statistics on a "per head" basis. There are several reasons for this, but the differences between the two data sets are normally small.
Population projections are taken from national sources where these are available, but for some countries they are based on UN or Eurostat projections; the projection for the world comes from UN. All population projections require assumptions about future trends in life expectancy, fertility rates and migration. Often, a range of projections is produced using different assumptions about these future trends. The estimates shown here correspond to the median or central variants.
In 2006, OECD countries accounted for 18% of the world's population of 6.5 billion. China accounted for 20% and India for 17%. Within OECD, the United States accounted for 25% of the OECD total, followed by Japan (11%), Mexico (9%), Germany (7%) and Turkey (6%).
Between 1993 and 2006, the population growth rate for all OECD countries averaged 0.7% per annum. Growth rates much higher than this were recorded for Mexico and Turkey (high birth rate countries) and for Australia, Canada, Luxembourg, Ireland, New Zealand and United States (high net immigration). In the Czech Republic, Hungary and Poland, populations declined from a combination of low birth rates and net emigration. Growth rates were very low, although still positive, in Germany and the Slovak Republic.
The population growth of OECD countries is expected to slow down in the coming decennia. Until the middle of this century, the population of OECD countries is expected to grow by less than 0.3 per cent per annum.
Total fertility rates have declined dramatically over the past few decades, falling on average from 2.7 in 1970 to 1.6 children per woman of childbearing age in 2005. By 2005, the total fertility rate was below its replacement level of 2.1 in all OECD countries except Mexico and Turkey. In all OECD countries, fertility rates have declined for young women and increased at older ages, because women are postponing the age at which they start their families.