This annex contains data on some main economic series which are intended to provide a background to the recent economic developments in the OECD area described in the main body of this report. Data for 2009 to 2011 are OECD estimates and projections. The data on some of the tables have been adjusted to internationally agreed concepts and definitions in order to make them more comparable as between countries, as well as consistent with historical data shown in other OECD publications. Regional totals and sub-totals are based on those countries in the table for which data are shown. Aggregate measures contained in the Annex, except the series for the euro area (see below), are computed on the basis of 2005 GDP weights expressed in 2005 purchasing power parities (see following page for weights). Aggregate measures for external trade and payments statistics, on the other hand, are based on current year exchange rates for values and base-year exchange rates for volumes.