Population 754 Economic conditions 85 History 82 Statistics 81 Population forecasting 66 Social conditions 60 Population policy 59 Demography 54 Birth control 53 Congresses 50 Labor supply 38 Fertility, Human 37 Food supply 35 Mathematical models 35 Population genetics 35 Populism 32 Economic aspects 28 Animal populations 27 Agriculture 23 Emigration and immigration 23 Housing 21 Politics and government 21 Rural population 21 Statistics, Vital 21 Ecology 19 Migration, Internal 19 Economic development 18 Natural resources 18 Urbanization 17 Population research 16