Labour productivity is defined as GDP per hour worked; where GDP for each country refers to its Gross Domestic Product, in national currency, at constant prices, OECD base year 2000, and output for country groups / zones GDP refers to the Gross Domestic Product, in US dollars, at constant prices, constant PPPs, OECD base year 2000. Labour input is defined as total hours worked of all persons employed. The data are derived as average hours worked from the OECD Employment Outlook, OECD Annual National Accounts, OECD Labour Force Statistics and national sources, multiplied by the corresponding and consistent measure of employment for each particular country. The measures of labour productivity are presented as indices and as rates of change. Source: OECD Employment Outlook, OECD Labour Force Statistics, OECD Annual National Accounts and OECD Quarterly National Accounts, and national sources.