Definition

The number of inhabitants of a given region, i.e. its total population, can be measured as either its average annual population or as the population at a specific date during the year considered. The average population during a calendar year is generally calculated as the arithmetic mean of the population on 1 January of two consecutive years, although some countries estimate it on a date close to 1 July.

The index of geographic concentration offers a picture of the spatial distribution of the population. It compares the share of population and land area over all regions in a given country, and it takes into account both within- and between-country differences in the size of all regions. This index lies between 0 (no concentration) and 100 (maximum concentration) and is suitable for international comparisons.

For more statistics on economic, environmental and social issues visit online the OECD Factbook 2010.