Frequencies for first 10,000 rows of pregnant variable in nhamcsopd1998 dataset :

 if female, |
 is patient |
  pregnant? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,055       10.55       10.55
          2 |      4,642       46.42       56.97
          3 |        708        7.08       64.05
          4 |      3,595       35.95      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016