As a cursor below the graph runs through the years, the pyramid shows the population distribution of males and females by age group. You can stop it and a mouse-over will highlight the age group of each bar for males and females.
Here is the present Graph showing that edge of the baby-boomers hitting the social security bracket, and two mild periods of reduced birth rates around 1990 and 1970 (why???... are these just the dampened oscillations of the baby-boom... born around 1950 we would have our children born around 1975-1980 and grandchildren around 2000 to 2005? or do they cue off economic boom and bust... what was the impact of Aids )