Backwrd population projection by a generalized inverse.
D000367:Age Factors; D001530:Belgium; D001723:Birth Rate; D002031:Bulgaria; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008722:Methods; D008962:Models, Theoretical; D009026:Mortality; D011158:Population Growth; D012737:Sex Factors; D014481:United States