Adolescent Adult Aged Aged, 80 and over Developed Countries--statistics & numerical data Developing Countries--statistics & numerical data Female Glomerulonephritis--epidemiology Glomerulonephritis, Membranoproliferative--epidemiology Glomerulonephritis, Membranous--epidemiology Glomerulosclerosis, Focal Segmental--epidemiology Humans Male Middle Aged Prevalence Singapore--epidemiology Socioeconomic Factors Time Factors Young Adult