Source: OECD Main Economic Indicators (updated monthly) - Purchasing power parities (PPPs) are the rates of currency conversion that eliminate the differences in price levels between countries. Per capita volume indices based on PPP converted data reflect only differences in the volume of goods and services produced. Comparative price levels are defined as the ratios of PPPs to exchange rates. They provide measures of the differences in price levels between countries. The PPPs are given in national currency units per US dollar. The price levels and volume indices derived using these PPPs have been rebased on the OECD average.

The figures for the zones are OECD estimates. They are derived using the PPPs and GDP of their constituent countries.

Euro Denominated Series From the February 2002 edition of MEI, national data for Euro area member countries have been published in euro.

The option chosen by OECD has been to convert data for periods prior to entry into European Monetary Union (EMU), i.e. prior to 1999 for all members apart from Greece which acceded in 2001, from the former national currency using the appropriate irrevocable conversion rate. Such a presentation facilitates comparisons within a country over time and ensures that historical evolution (i.e. growth rates) is preserved.

However, pre-EMU euro are national units and are not always suitable to form area aggregates. For further details on this issue see the article by Schreyer and Suyker in Statistics Brief Number 2, February 2002 .

The "monetary unit" used to express these series is footnoted where appropriate and is shown as [year of accession][ISO currency code]euro. Historical data for Austrian series, for example, that were previously expressed in the unit ATS are now expressed as EUR (and footnoted as 1999 ATS euro). Note that, for all euro area countries, data for periods after accession (i.e. 1999 onwards, 2001 onwards for Greece) are expressed in true euro.