STATISTICS

Technical notes (continued)Energy production, primary, refers to the first stage of production of various formsof energy (from sources that involve only extraction or capture, with or withoutseparation from contiguous material, cleaning or grading, before the energyembodied in that source can be converted into heat or mechanical work, convertedinto a common unit (metric ton of oil equivalent) (see United Nations publicationConcepts and Methods in Energy Statistics, with Special Reference to EnergyAccounts and Balances, 1982). The data refer to the following commercial primaryenergy sources: hard coal, lignite, peat, oil shale, crude petroleum, natural gasliquids, biodiesel, alcohol, natural gas, primary steam/heat, and electricitygenerated from hydro, nuclear, geothermal, wind, tide, wave and solar sources.Source of the data: The Energy Statistics Yearbook (information provided by theIndustrial and Energy Statistics Section of the United Nations Statistics Division asof 18 December 2013).Exchange rates are shown in units of national currency per US dollar and refer toend-of-period quotations. The exchange rates are classified into broad categories,reflecting both the role of the authorities in the determination of the exchangeand/or the multiplicity of exchange rates in a country. The market rate is used todescribe exchange rates determined largely by market forces; the official rate is anexchange rate determined by the authorities, sometimes in a flexible manner. Forcountries maintaining multiple exchange arrangements, the rates are labelledprincipal rate, secondary rate, and tertiary rate.Source of the data: The International Monetary Fund, International FinancialStatistics database (last accessed 6 January 2014). For those currencies for whichthe IMF does not publish exchange rates, non-commercial rates derived from theyear-end operational rates of exchange for United Nations programmes are shown,as published by the United Nations Treasury, available at http://www.un.org/Depts/treasury/ (last accessed 6 January 2014).Fertility rate: The total fertility rate is a widely used summary indicator of fertility.It refers to the number of children that would be born per woman, assuming nofemale mortality at child bearing ages and the age-specific fertility rates of aspecified country and reference period. Unless otherwise indicated, the data are thefive-year average for the reference period 2010-2015.Source of the data: United Nations, Department of Economic and Social Affairs,Population Division (2013), World Population Prospects: The 2012 Revision,available at http://esa.un.org/unpd/wpp/Excel-Data/population.htm; supplementedby official national statistics published in the United Nations DemographicYearbook 2012, Table 4, available at http://unstats.un.org/unsd/demographic/products/dyb/dyb2012.htm; and data compiled by the Secretariat of the PacificCommunity (SPC) Statistics and Demography Programme, Population anddemographic indicators, available at http://www.spc.int/sdp.World Statistics Pocketbook 225