> Using 1999 data [1], 52% of US families had no children, 20% had one child, 18% had two children, 7% had 3 children, and 3% had 4 or more children. 52% no ch

> Using 1999 data [1], 52% of US families had no children, 20% had one child, 18% had two children, 7% had 3 children, and 3% had 4 or more children. 52% no children made do a double take and I'm glad I did. I think the issue with your calculation is that some of the families will eventually have more children than they did at the time of measurement. So number of children is biased downwards.