title: The UK population at the start of the 21st century.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019352:Censuses; D003710:Demography; D004641:Emigration and Immigration; D005260:Female; D005298:Fertility; D049674:History, 21st Century; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends; D011157:Population Dynamics; D006113:United Kingdom / Q000453:epidemiology